Petrarctus rugosus (H. Milne Edwards, 1837 ) Holthuis, 2002

Holthuis, Lipke B., 2002, The Indo-Pacific scyllarine lobsters (Crustacea, Decapoda, Scyllaridae), Zoosystema 24 (3), pp. 499-683 : 529-541

Petrarctus rugosus (H. Milne Edwards, 1837) n. comb.

( Figs 12 ; 13 )

Scyllarus rugosus H. Milne Edwards, 1837: 283 ; 1838: 168. — White 1847: 67. — Morice 1875: 110. — Pfeffer 1881: 47. — Holthuis 1946: 89, pl. 7 fig. c, pl. 8 fig. a, pl. 9 fig. c; 1968: 288; 1991: 225, figs 425, 426. — Harada 1962: 128; 1965: 36. — Naiyanetr 1963: 68; 1980: 22; 1998: 12, 44, fig. — Prasad & Tampi 1969: 84. — Stephenson et al. 1970: 492. — Berry 1974: 13, 14. — Burukovsky 1974: 106; 1983: 149. — Tampi & George 1975: 34, figs 34-36. — Phillips et al. 1980: 70. — Prasad et al. 1980: 83, fig. 10. — Miyake 1982: 84. — Prasad 1983: 144, fig. 3a. — Chan & Yu 1986: 150, pl. 1, pl. 8 fig. A, pl. 10 fig. C. — Sekiguchi 1986a: 1289-1291; 1986b: 15, 17; 1987a: 331; 1987b: 415, 417, 418, fig. 48; 1988: 3; 1989b: 457. — Barnett 1989: 123, 126, fig. 3. — Mutchacheep 1992: 26. — Chan & Yu 1993: 201, coloured fig. — Huang 1994: 564. — McWilliam et al. 1995: 564. — Nguyên Van Chung & Pham Thi Du 1995: 105. — Hu & Tao 1996: 144, pl. 3 figs 3, 4. — Chan 1998: 1043, 3 figs n.n.

Arctus tuberculatus Bate, 1888: 70 , pl. 10 figs 1, 2. — Doflein 1900: 132. — Lanchester 1902: 557.

Scyllarus tuberculatus – Nobili 1903: 12. — Pearson 1905: 90. — De Man 1916: 68, 89. — Barnard 1926: 123, pl. 10; 1950: 560. — Dawydoff 1952: 136. —? Prasad & Tampi 1968: 116, fig. 1. — Zarenkov 1971: 167. — Kensley 1981: 30. — Huang 1994: 564 [non Scyllarus tuberculatus – De Man 1924: 53, fig. 18 (= Scyllarus demani Holthuis, 1946 )].

Scyllarus ragosus – Vine 1986: 107.

Scyllarus spec. A? – Berry 1974: 13, figs 36, 38, 45-47. Scyllarus cultrifer – Hwang & Yu 1983: 264, fig. 5 [non Arctus cultrifer Ortmann, 1897 ].

Non Arctus rugosus Yokoya, 1933: 46 , fig. 24 (= Scyllarus brevicornis Holthuis, 1946 ).

TYPE MATERIAL. — The type (or types) were deposited at the MNHN, but at present they cannot be located. TYPE LOCALITY. — India, coast of Pondichery.

MATERIAL EXAMINED. — Red Sea. Sudan, Port Sudan, II.1979, J. C. Miquel, 1 16 mm, 1 16 mm ( RMNH D 39327). — Off Tokar Delta, 18°40’N, 38°00’E, otter trawl, 10-20 m, 1979, J. Branford, 1 ov. 22 mm ( BM).

Ethiopia, near Massawa, 21.III.1958, A. Ben Tuvia & O. H. Oren, 3 14-16 mm ( RMNH D 18353). — Dahlak Archipelago, E of Museri Id, FV Negus Salomon , stn 12, 15°35’N, 40°44’E, 37 m, bottom flat with sponges, 23.X.1965, 1 11 mm ( RMNH D 23654).

Kenya. N of Ras Ngameni, southern Formosa Bay, RV Shakwe, 9-37 m, 26.VI.1969, A. J. Bruce, 1 16 mm ( RMNH D 27473). — Off Ras Ngameni, southern Formosa Bay, EAMFRO (East African Marine Fisheries Organisation), cruise 320, trawl stn 10, 24 m, trawled, 21.II.1971, A. J. Bruce, 5 16- 18 mm ( RMNH D 30588 ).

Tanzania. S of Dar es Salaam, RV Manihine, cruise 309, trawl stn 12, 7°48.0’S, 39°34’E, 16-20 m, 14.VI.1970, A. J. Bruce, 1 11 mm ( RMNH D 28599).

Mozambique. NE of Beira, RV Prof. Mesyatsev, Haul No. 50, 19°37.0’S, 35°43.7’E, 27-33 m, 20.I.1976, B. G. Ivanov, 1 ov. 21 mm ( VNIRO).

Madagascar. NW coast. RV Vauban, 12°55.2’S, 48°28.2’E, trawl, 42 m, 2.VIII.1973, A. Crosnier, 1 ov. 18 mm (MNHN-Pa 580). — RV Vauban, 13°04’S, 48°37’E, trawl, 23 m, 9.V.1973, A. Crosnier, 2 ov. (MNHN-Pa 585 and RMNH D 39326). — Baie d’Ambaro, 13°20’S, 48°40’E, trawl, shrimp grounds, 10-20 m, A. Crosnier, 2 10 and 17 mm (MNHN-Pa 589). — Nosy Bé, 13°20’S, 48°20’E, 1960, A. Crosnier, 1 ov. 20 mm (MNHN-Pa 591). — Tany Kely, near Nosy Bé, 20 m, V.1966, A. Crosnier, 2 17 and 18 mm, 1 ov. 16 mm (MNHN-Pa 583 and RMNH D 39328). — 13°27’S, 48°12’E, trawl, 27-30 m, 24.VIII.1967, R. Plante, 1 18 mm (MNHN-Pa 584). — Near Majunga, RV Vauban, stn CH 52, 15°21.0’S, 46°12.5’E, trawl, 150 m, 8.XI.1972, 4 10-12 mm, 5 8-11 mm (3 ov. 10-11 mm) (MNHN-Pa 569; RMNH D 39325) .

Burma. IIOE, RV Anton Bruun, cruise 1, stn 38, 14°07’N, 97°05’E, trawl, 69-73 m, 30.III.1963, 1 11 mm ( USNM). — Stn 39A, 14°52’N, 96°39’E, trawl, 48-64 m, 31.III.1963, 1 13 mm ( USNM).

Thailand. Between Naklua and Si Racha, Chonburi Province, about 35 m, from fishermen, 18 and 25.XI.1986, A. C. J. Burgers & L. B. Holthuis, 5 18-20 mm, 1 non-ov. 19 mm, 4 ov. 17-22 mm ( RMNH D 30637). — Laem Chabang near Si Racha, Chonburi Province, 10 m, trawled, from fishermen, 11.I.1991, A. C. J. Burgers & L. B. Holthuis, 1 13 mm ( RMNH D 38686). — Near Koh Smet, Rayong Province, otter trawl, 15.X.1963, P. Naiyanetr, 2, 2 ( RMNH D 37611). — Koh Chong, Rayong Province, 35 m, 19-20.X.1962, P. Naiyanetr, 1 17 mm ( RMNH D 18352). — Gulf of Thailand, off Pattani Bay, from fishermen, 14.XI.1985, C. Swennen No. 338, 1 20 mm, 1 13 mm ( RMNH D 49589).

South China Sea. Hong Kong, 1867, capt. J. Schnehagen, 1 14 mm ( ZMH). — E of Hainan, RV Cape St. Mary, stn 108, 19°40’N, 111°31’E- 19° 35’N, 111°40’E, otter trawl, 101 m, 18.XII.1958, A. J. Bruce ( RMNH D). — Near Macclesfield Bank, RV Cape St. Mary, cruise 3/64, stn 26, trawl, stn 156, 16°04.2’N, 114°41.8’E- 16°04.0’N, 114°39.0’E, 80 m, white muddy sand and coral, 14.VI.1964, A. J. Bruce, 1 9 mm ( RMNH D 30936). — Vietnam, RV Cape St. Mary, cruise 7/64, stn 110, trawl, stn 156, 8°01.6’N, 107°41.2’E- 8°04.1’N, 107°42.9’E, 59 m, sand, 19.XI.1964, A. J. Bruce, 1 23 mm ( RMNH D 45639). — Vietnam, RV Lanessan, entr. No. 7, 1930, A. Krempf, 1 21 mm (MNHN-Pa 290).

Taiwan. Takao (= Kaohsiung), 10.XII.1907, H. Sauter, 2, 1 ( ZMB) ; 3-4.XII.1914, F. Baker, 3 15-17 mm, 7 15-21 mm (of which 5 ov. 15-21 mm) ( USNM; RMNH D 14590). — Ping Tong , Tong-Kang County, c. 100 m deep, sand and mud, baby-shrimp trawlers, 2.XII.1984, T. Y. Chan, 1 17 mm, 1 ov. 15 mm ( RMNH D 49588) .

Philippines. Mindoro Strait, MUSORSTOM 3, stn CP 121, 12°08’N, 121°18’E, 73-84 m, 3.VI.1985, 1 14 mm, 1 non-ov. 9 mm, 2 ov. 14 and 15 mm (MNHN-Pa 1090). — Observatory Id (N), S 55°W 10.7 miles, Linapacan Strait, RV Albatross, stn D 5335, 11°37’15”N, 119°48’45”E, 84 m, sand and mud, 18.XII.1908, 1 11 mm ( USNM). — Balukbaluk Id (N), S 59°W 6.25 miles, RV Albatross, stn D 5134, 6°44’45”N, 121°48’E, 46 m, fine sand, 7.II.1908, 1 juv. 8 mm ( USNM). — Off Jolo Id, Th. Mortensen Pacific Expedition, c. 22 m, dredge, sand and coral, 17.III.1914, 1 13 mm ( UZM).

Indonesia. Macassar Strait. CORINDON, stn 206, 85- 79 m, 30.XI.1980, 1 8 mm, 1 ov. 10 mm (MNHN-Pa 1054). — Java Sea, 1907-1911, RV Gier, 1 20 mm ( ZMA). — Java Sea, Th. Mortensen Kai Ids Expedition, stn 106, 5°50’S, 106°16’E, 32 m, sand, 5.VIII.1922, 1 18 mm ( UZM). — SW of Pulau Tarupa Kecil, NE Take Bone Rate (Tiger Ids), S of Sulawesi (= Celebes), Indonesian-Dutch Snellius II Expedition, 6°31.3’S, 121°6.5’E, 48 m, sandy bottom with spatangoid echinoderms, 1.2 m Agassiz trawl, 16.X.1984, 1 specimen ( RMNH D 45638). — Ambon, Moluccas, 1861-1864, E. W. A. Ludeking, 1 ov. 21 mm ( RMNH D 1516). — Arafura Sea, RV Challenger, stn 190, 8°56’S, 136°5’E, trawl, 90 m, green mud, 12.IX.1874, 1 15 mm, 1 non-ov.

17 mm, 1 ov. 14 mm; all syntypes of Arctus tuberculatus Bate, 1888 ( BM).

Off west coast of Wasir Id, Wokam, Aru Ids, Mariel King Memorial Expedition, 5°30’S, 134°12’E, 50- 59 m, mud and sand, 15.VI.1970, 1 10 mm ( WAM). — West of Uojir Id, Wokam, Aru Ids, 5°37’S, 134°18’E, 55-66 m, mud and fine shelly grit, 1 16 mm ( WAM). — North of Doe Rowa, N of Nuhu Roa, Kai Ids, 5°32’S, 133°41’E, 27-37 m, sand and rubble, 11.VI.1970, 1 ov. 14 mm ( WAM).

Australia. N Queensland, off Cairns, trawl, 20 m, mud, I.1983, Clive Jones, 2 19 and 21 mm ( RMNH D). — Low Isles, NE of Cairns, 20 m, sandy mud, 25.VIII.1984, Clive Jones, 2 (largest ov.) 18 and 21 mm ( RMNH D 49590).

New Caledonia. LAGON, stn 376, Grand Récif Sud, 22°34’S, 167°06’E, 75-76 m, 21.I.1985, B. Richer de Forges, 1 12 mm (MNHN-Pa 1203).

Vanuatu. MUSORSTOM 8, stn CP 1086, 15°36.58’S, 167°16.32’E, 182-215 m, 5.X.1994, B. Richer de Forges, 1 10 mm, 2 7 mm ( RMNH D 48741). — Stn CP 1103, 15°3.87’S, 167°7.76’E, 163-165 m, 7.X.1994, B. Richer de Forges, 1 13 mm (MNHN-Pa 1901).

Fiji Islands. MUSORSTOM 10, stn CP 1358, SE of Viti Levu, 17°48.5’S, 178°46,7’E, 80-120 m, 13.VIII.1998, 1 10 mm, 1 11 mm (MNHN-Pa 1900).

DISTRIBUTION. — The type locality of Scyllarus rugosus is Pondichery, India. That of Arctus tuberculatus is the Arafura Sea (8°56’S, 136°5’E). The range of the species extends from the Red Sea and East Africa to Japan or Taiwan, the Philippines, Indonesia, Australia, New Caledonia, Vanuatu and the Fiji Islands. A chart of its distribution was published by Chan (1998). The original records in the literature are (references to previously published records are omitted): Southern Red Sea near Massawa and near Museri Island, 15°35’N, 40°44’E ( Holthuis 1968); Red Sea South of 15°N and Strait of Bab al Mandab ( Zarenkov 1971); off Mozambique, 26°17’S, 33°10’E ( Barnard 1926); Indian Ocean ( White 1847), Pondicherry, India (H. Milne Edwards 1837); Pearl Banks, Aripu Reef and Galle, Gulf of Manaar, Sri Lanka ( Pearson 1905); Andaman Sea off Thailand ( Naiyanetr 1980); Japan ( Doflein 1900); Taiwan ( Hu & Tao 1996), Hsing-Ta and Tong-Kang, Taiwan ( Chan & Yu 1986); Keelung, Taiwan ( Hwang & Yu 1983); China (based on previous Taiwan records) ( Huang 1994); Hong Kong ( Pfeffer 1881); Viet Nam ( Morice 1875; Nguyên Van Chung & Pham Ti Dhu 1995); Hon Tcha reef, Pulo Condore, Viet Nam ( Dawydoff 1952); Gulf of Thailand ( Naiyanetr 1963, 1980, 1998; Mutchacheep 1992); Chonburi, Rayong, Pattani, Gulf of Thailand ( Naiyanetr 1998); Kelantan, Malaya ( Lanchester 1902); Singapore ( Nobili 1903); Ambon, Indonesia ( Holthuis 1946); Arafura Sea, 8°56’S, 136°5’E ( Bate 1888); Gulf of Carpentaria, N Australia ( McWilliam et al. 1995); Torres Strait, Australia ( McWilliam et al. 1995); North Queensland ( Barnett 1989; McWilliam et al. 1995); Moreton Bay, Queensland, Australia ( Stephenson et al. 1970). The record of the species from Japan is doubtful: the only original record is by Doflein (1900), all later authors only refer to Doflein. Doflein stated: “Mein Exemplar stammt aus Japan ohne genauere Angabe leg. Salmin”. C. L. Salmin was not a collector but a dealer in natural history objects in Hamburg. It is well-known that the material offered by dealers often had unreliable labels. This, combined with the fact that notwithstanding the extremely intense study of the Japanese marine fauna in the last decades, P. rugosus n. comb. has not been found again in Japan, makes the correctness of the old label rather doubtful. The species, however, is quite common in Taiwan. The specimens reported upon by Pfeffer (1881) and Bate (1888) have been re-examined.

HABITAT. — The examined material came from depths between 10 and 182(-215) m, 90% was taken at less than 100 m depth, and 60% between 20 and 60 m. Chan & Yu (1993) also gave the depth as “ 20- 60 m (rarely 200 m)”. A Red Sea specimen was taken at 37 m ( Holthuis 1968). Barnard’s (1926) specimen was said to be taken at 415 m. Pearson (1905) report- ed the species from depths of 8-10, 8-13, and 16.5- 26 m. The species inhabits flat and even bottoms and therefore is often taken by trawl. The nature of the bottom on which the examined material was found is described as sand, sometimes in combination with mud, coral, rubble, or with spatangoid echinoderms; sometimes the bottom is said to be fine sand, or white muddy sand and coral, or shelly grit, or sandy mud, or green mud. Pearson’s (1905) material was taken from bottoms of coarse sand, sometimes with small corals, or with “fine green weeds and small pearl oysters”.

DESCRIPTION

The rostrum is blunt and bears a low and blunt dorsal tubercle, behind which there are three diverging rows of small tubercles, which sometimes are fused to a low ridge. The pregastric tooth is absent and replaced by a short somewhat curved transverse row of two to four tubercles, the outer of which are the larger; this row continues laterally into the anterior submedian ridge. The gastric tooth is broad and blunt, it is followed by two rows of four or five blunt tubercles that converge posteriorly. The cardiac tooth is quite distinct and has a blunt apex which sometimes is slightly two-topped; the tooth is followed by a double row of four large blunt tubercles. The anterior and posterior submedian ridges bear about two to four blunt tubercles each. Both the postrostral and the branchial carinae are deeply interrupted by the cervical groove. In the gap of the branchial groove no tubercle is visible. The branchial carina ends anteriorly in two teeth that are placed, one behind the other on the inner orbital margin; the posterior of these two teeth is low and not very distinct, behind it the carina shows two small teeth or tubercles. The posterior branchial carina is straight and ends in a blunt anterior tooth. It bears a double row of five to eight blunt tubercles. Between the posterior branchial carina and the posterior postrostral carina there is a longitudinal row of about five or six low and rounded intermediate tubercles, placed closer to the former than to the latter carina; a larger blunt tubercle is found between the intermediate row and the submedian carina. The lateral margin of the carapace shows three anterolateral, two or three mediolateral and a double row of nine or 10 posterolateral tubercles. Two, seldom three, tubercles may be seen behind the orbit. The intercervical area bears one or two rows of two to four tubercles. The space between the posterolateral and posterior branchial carina is entirely filled by tubercles. The marginal groove along the posterior margin of the carapace is wide. Before it the carapace bears a transverse row of smallish tubercles, the two submedian of which are larger than the rest. Behind the marginal groove there is a transverse row of small rather indistinct tubercles, the submedian two may be larger than the rest. The middle of the posterior margin of the carapace is shallowly and bluntly V-shapedly incised.

In the first abdominal somite the median transverse groove shows only in the extreme lateral parts; the rest of the dorsal surface of the somite is smooth, without grooves or tubercles. In the next four somites the anterior half (that disappears under the previous somite when the abdomen is stretched) is entirely smooth. The posterior half of these somites is raised and bears an elevated longitudinal median carina, which is by far highest on the third somite and may overhang the posterior margin of the somite and the median transverse groove. On either side of the median carina there are some tubercles, which are partly fused with the carina and give the median structure a somewhat lobulated margin. On either side of the median carina the upper surface of somites II to V there are two parallel transverse carinae, separated by a deep groove. The posterior of each pair of carinae is simple with a smooth upper surface, having the posterior margin crenulate in somites IV and V, but there are no tubercles. The anterior carina of each pair is smooth in the second and usually also in the third somite, ending laterally in a forked or bilobate tip; in somites IV and V, sometimes also in somite III, it is more lobulated. The posterior margin of the first somite is bluntly V-shapedly incised. No such incision is visible in the following somites, although the second may have a slight median emargination. The median carina of somite IV even may end in a small posterior point. The pleura of somite I is very short and rounded with an irregularly lobulated margin. The pleura of the following somites are rather broad, the apex is blunt and directed downward. They bear a median carina and have the posterior margin crenulate or serrate (in the second pleura also the anterior margin). The dorsal surface of somite VI is tuberculate, the posterior margin is crenulate. Of the four bosses in the hard part of the telson, the anterior pair is larger than the posterior. The outer of the two pairs of teeth at the end of the calcified part of the telson are broad and triangular with a blunt top, the teeth of the inner pair are smaller and narrower, but the top is also blunt.

The anterior margin of the antennular somite is about straight, showing only a very inconspicuous low and blunt tooth in the middle of each half.

The anterior margin of the last (sixth) segment of the antenna is slightly convex and bears five to seven (usually six) long teeth, while a much smaller tooth is placed on the inner margin. The large teeth taper regularly towards the top. The spaces between the teeth are rather wide. The fifth segment shows no carina on the dorsal surface. The anterior margin of the fourth segment bears five to seven distinct teeth, the innermost of which is largest. The outer margin of the segment bears four or five teeth (not including the apical tooth), each of which bears a (sometimes tuberculated) dorsal ridge. The median carina of the segment is very high and sharp.

The epistome is not much sunken and shows a hardly visible minute median incision in the anterior margin.

The first pereiopods are very heavy. The following legs are slender. The dactylus of the second leg is longer than either that of the first or third leg, it is less than twice as long as that of the fourth. The dactyli of legs three to five are velvety pubescent in the basal part, sometimes with an inconspicuous fringe of short hairs. The third leg has the propodus as wide as the merus and not conspicuously wider than that of the second and fourth legs, it bears a distinct row of hairs along both the dorsal and ventral margins, but the outer surface shows no grooves. The propodi of the other legs do not have hairy fringes, but the propodus of the fourth leg may have very short hairs in the proximal part of the lower margin.The carpus of the pereiopods is short and has no tooth on the anterior margin. The merus of P.3 to P.5 has a dorsal fringe of hairs, and a short velvety pubescence on the lower surface; there is a longitudinal hairy groove in the upper part of the outer surface. In the females the distal process of the propodus of the fifth leg is longer than half the dactylus.

The thoracic sternum is deeply U-shapedly incised anteriorly; it ends in two strong bluntly topped anterolateral teeth. Immediately behind these teeth there is a tubercle formed by two anteriorly converging short carinae. A median tubercle is present in the anterior half of the second to fifth sternites. The lateral part of the sternum is raised. The posterior margin of the last sternite is tuberculated.

The pleopod of abdominal somite II of the male is well-developed, the endopod being slightly longer than the exopod, both are slender. The pleopods of somites III to V have the exopods very narrow, that of the third somite is about half as long as that of the second, those of the fourth and fifth somites are still smaller. The pleopod endopods of somites III to V are elongate, being about half as long as their respective exopods.

Size

The type specimen of Scyllarus rugosus was said to have a tl. of 54 mm, which corresponds to a carapace length of roughly 17 mm. The type specimens of Arctus tuberculatus are about as long or slightly smaller (one male cl. 15 mm, one nonovigerous female cl. 17 mm, one ovigerous female cl. 14 mm). In the examined material the carapace length of the males varies between 8 and 23 mm (70% between 14 and 20 mm), of the non-ovigerous females cl. varied between 8 and 21 mm, and of the ovigerous females between 10 and 22 mm (89% between 14 and 22 mm).

Colour

The first colour description published of the species is the one by Barnard (1926: 123): “General colour red, paler towards end of abdomen, mottled with paler red and white, most of the tubercles have white tips, outer margin of 2nd joint of antennae and the smooth dorsum of 1st abdominal segment violet”. Coloured photographs of live or fresh specimens were published by Chan & Yu (1986: pl. 1 fig. E, pl. 8 fig. A, pl. 10 fig. C; these show the animal in ventral, dorsal and lateral view; their pl. 1 figs A-D shows a preserved specimen in colour). They described the colour as follows ( Chan & Yu 1986: 151): “Dorsal surface brown and dark brown. Teeth at antennal segment VI, abdominal pleura III and IV, abdominal segment V and VI, tailfan and ventral surface whitish. Eyes light brown. Dorsal surface of pereiopods brown and white. Dorsal surface of abdominal tergite I blue, color more concentrated at articulate surface. Lateral surfaces of abdominal somites I and II somewhat orange. Eggs orange-yellow”. A new colour photograph of the species in dorsal view was later published by the same authors ( Chan & Yu 1993: 201).

Larvae

Prasad & Tampi (1968) described and figured what they thought to be the nisto stage of this species from the Laccadive Archipelago, Western Indian Ocean. Phyllosomata, supposedly of this species, were described and figured by Berry (1974) from Natal as Scyllarus sp. A. Various stages of phyllosomata from the Red Sea, South Africa, eastern and western Indian Ocean, supposedly belonging to this species, were dealt with by Tampi & George (1975), Prasad et al. (1980) and by Prasad (1983). Barnett (1989) described and figured a late phyllosoma from the Great Barrier Reef, 18°35’- 19°10’S, 146°30’- 147° 00’E.

Petrarctus brevicornis ( Holthuis, 1946) n. comb.

( Figs 14 ; 67A, B )

Scyllarus brevicornis Holthuis, 1946: 92 . — Harada 1962: 128; 1965: 36. — Burukovsky 1974: 106. — Phillips et al. 1980: 69. — Miyake 1982: 84. — Baba et al. 1986: 163, 286, fig. 113. — Chan & Yu 1986: 156, pl. 5, pl. 9 figs C, D; 1993: 207, col. fig. — Sekiguchi 1986a: 1289; 1986b: 15, 17; 1987a: 331; 1988: 3. — Sekiguchi & Tagawa 1987: 11, text-fig. 1, pl. 2. — Holthuis 1991: 222, figs 419, 420. — Wang 1991: 218, fig. 178. — Huang 1994: 564. — Wang et al. 1998: 447, 448.

Arctus rugosus Yokoya, 1933: 46 , fig. 24 [non Petrarctus rugosus (H. Milne Edwards, 1837) n. comb.].

TYPE MATERIAL. — Holotype: male dried out and in very poor condition (Fishery Institute, Tokyo University ).

ETYMOLOGY. — The specific epithet brevicornis (short horns) refers to Yokoya’s (1933: 48) remark that the antennular peduncle is short. Chan & Yu (1993) proposed the vernacular name “Blue-back locust lobster”.

TYPE LOCALITY. — Japan, Southern Bungo Strait.

MATERIAL EXAMINED. — Western Indian Ocean. Zanzibar. RV Manihine, cruise 334, stn D8, 5°30.5’S, 39°06.0’E, dredge, 155 m, 3.I.1972, 1 ov. 18 mm ( RMNH D 49570).

Madagascar. NW coast, RV Vauban, stn CH 130, trawl, 170-175 m, 15°20’S, 46°11.5’E, 19.I.1975, 2 (MNHN-Pa 570). — Stn CH 52, 15°21.0’S, 46°12.5’E, 150 m, 8.XI.1972, 1 ov. 16 mm (MNHN-Pa 574).

East China Sea. 29°28.6’N, 126°56.3’E, 104 m, 19.VII.1985, K. I. Hayashi don., 1 ov. 16 mm ( RMNH D 38506 ).

Taiwan. Ta-Chi, I-Lan County, c. 100 m, sand and mud, baby-shrimp trawl, 18.V.1985, T. Y. Chan leg. et don., 1 ov. 18 mm ( RMNH D 39374).

South China Sea. RV Cape St. Mary, S of Hong Kong, cruise 4/65, stn 13, trawl 354, 21°20.0’N, 114° 25.6’E, 84 m, mud, 24.IV.1965, A. J. Bruce, 1 18 mm ( RMNH D 49571). — SW of Hong Kong, cruise 7/63, stn 46, trawl 108, 21°12.0’N, 113°30.5’ E, 53-60 m, muddy sand, 17.XII.1963, A. J. Bruce, 1 7 mm ( RMNH D 49572). — NE of Hainan, 19°35’N, 111°40’E, No. 812.3.11-12, otter trawl, 101 m, 18.XII.1958, A. J. Bruce, 2 11 and 16 mm ( RMNH D 49587).

Philippines. MUSORSTOM 1, North of Lubang Id, stn 56, 13°53.3’N, 120°10.7’E, 129-134 m, 26.III.1976, 1 juv. 5 mm (MNHN-Pa 1803). — Stn 62, 14°00.6’N, 120°13.7’E, trawl, 179-194 m, 27.III.1976, 1 10 mm ( RMNH D 48759).

MUSORSTOM 2, stn 6, North of Lubang Id, 13°56.4’N, 120°22.3’E, trawl, 136-152 m, 20.XI.1980, 1 ov. 14 mm (MNHN-Pa 592).

Chesterfield Islands. CHALCAL 1, stn CP 9, 19°44.12’S, 158°28.52’E, trawl, 280 m, 21.VII.1984, 1 (MNHN-Pa 794).

CORAIL 2, stn CP 131, 19°25.49’S, 158°37.96’E, 215-217 m, 29.VIII.1988, B. Richer de Forges, 1

8 mm, 1 7 mm, 1 juv. 6 mm (MNHN-Pa 1304).

New Caledonia. BIOCAL, stn CP 42, 23°46’S, 167°13’E, 380 m, 30.VIII.1985, 1 juv. 10 mm (MNHN-Pa 1158).

MUSORSTOM 4, stn 173, 19°02.5’S, 163°18.8’E, 250-290 m, 17.IX.1985, 1 13 mm (MNHN- Pa 1153). LAGON, stn 396, Grand Récif Sud, 22°40’S, 167°09’E, 284 m, 23.I.1985, 1 14 mm (MNHN- Pa 1198). — Stn 835, Lagon Est, 20°46.8’S, 165°17.3’E, 135-150 m, 11.I.1987, 1 17 mm (photographed; MNHN-Pa 1279).

BATHUS 1, stn CP 667, 20°57.23’S, 165°34.59’E, 205-212 m, 14.III.1993, 1 8 mm, 1 7 mm ( RMNH D 48761). — Stn CP 712, 21°44.3’S, 166°35.3’E, 210 m, 19.III.1993, 1 6 mm (MNHN-Pa 1816). — Stn CP 713, 21°45.3’S, 166°36.8’E, 250 m, 19.III.1993, 1 11 mm ( USNM 1000669).

BATHUS 2, stn DW 715, 22°39.42’S, 167°10’E, 202-227 m, 10.V.1993, 1 6 mm (MNHN-Pa 1814). — Stn CP 728, 22°47.11’S, 167°28.11’E, 241- 245 m, 12.V.1993, 1 16 mm (MNHN-Pa 1815).

BATHUS 4, stn CP 952, off East coast, 20°34.70’S, 164°58.76’E, 270-316 m, 10.VIII.1994, 1 15 mm (MNHN-Pa 1873).

Loyalty Islands. MUSORSTOM 6, stn DW 399, 20°41.8’S, 167°00.20’E, 282 m, 14.II.1989, 1 juv. 5 mm (photographed) (MNHN-Pa 1817).

Vanuatu. MUSORSTOM 8, stn CP 1071, 15°36.63’S, 167°16.34’E, 180-191 m, 4.X.1994, 1

8 mm ( RMNH D 48760). — Stn CP 1077, 16°04.00’S, 167°06.09’E, 180-210 m, 5.X.1994, 3 8-11 mm (MNHN-Pa 1818). — Stn CP 1086, 15°36.58’S, 167°16.32’E, 182-215 m, 5.X.1994, 1

8 mm, 3 7, 11 and 12 mm (largest ov.), 1 juv. 5 mm (MNHN-Pa 1819). — Stn CP 1099, 15°05.39’S, 167°10.51’E, 275-284 m, 7.X.1994, 1 damaged c. 9 mm (MNHN-Pa 1820). — Stn CP 1102, 15°03.82’S, 167°08.68’E, 208-210 m, 7.X.1994, 1 7 mm (MNHN- Pa 1821).

Fiji Islands. Off Viti Levu. BORDAU 1, stn CP 1437, N of Viti Levu, 17°11’S, 178°46’W, 160-177 m, 2.III.1999, 1 8 mm (MNHN-Pa 1874).

MUSORSTOM 10, stn CP 1323, 17°16.1’S, 177°45.7’E, 143-173 m, 7.VIII.1998, 1 8 mm (MNHN-Pa 1810). — Stn CP 1349, 17°31.1’S, 178°38.8’E, 244-252 m, 11.VIII.1998, 2 juv. 9 mm (MNHN-Pa 1808). — Stn CP 1351, 17°31.1’S, 178°40.0’E, 292-311 m, 11.VIII.1998, 1 juv. 7 mm (MNHN-Pa 1811). — Stn CP 1355, 17°49.5’S, 178°49,4’E, 302-310 m, 12.VIII.1998, 1 12 mm, 1 13 mm (MNHN-Pa 1812). — Stn 1363, 18°12.4’S, 178°33.0’E, 144-150 m, 15.VIII.1998, 1 10 mm, 2 8 and 11 mm (MNHN-Pa 1804). — Stn CP 1366, 18°12.4’S, 178°33.1’E, 149-168 m, 15.VIII.1998, 1 9 mm (MNHN-Pa 1809). — Stn CP 1370, 18°12.3’S, 178°33.1’E, 113-123 m, 16.VIII.1998, 2 8 and 9 mm (MNHN-Pa 1805). — Stn CP 1371, 18°12.4’S, 178°32.8’E, 135-151 m, 16.VIII.1998, 1 11 mm (MNHN-Pa 1806). — Stn DW 1383, 18°18.4’S, 178°02.6’E, 230-251 m, 18.VIII.1998, 1 8 mm (MNHN-Pa 1813). — Stn CP 1385, 18°18.5’S, 178°05.2’E, 227-284 m, 18.VIII.1998, 2 8 and 11 mm, 5 8-14 mm ( RMNH D 48729). — Stn CP 1386, 18°18.5’S, 178°05.1’E, 230-344 m, 19.VIII.1998, 2 8 and 9 mm (MNHN-Pa 1807). — Stn CP 1387, 18°18.5’S, 178°04.7’E, 229-370 m, 19.VIII.1998, 2 11 and 12 mm, 6 9-12 mm (MNHN-Pa 1871). — Stn CP 1389, 241- 417 m, 19.VIII.1998, 7 8-12 mm, 10 10-16 mm (MNHN-Pa 1869; USNM 1000668 ). — Stn CP 1390, 18°18.6’S, 178°05.1’E, 234-361 m, 19.VIII.1998, 2 8 and 9 mm, 4 10-13 mm (MNHN-Pa 1869) .

DISTRIBUTION. — The type locality of the species is the southern Bungo Strait between Shikoku and Kyushu, Japan ( Yokoya 1933). Baba et al. (1986) also reported material from Bungo Strait. The same authors furthermore mentioned the species from Tosa Bay, Shikoku, as well as from the East China Sea, West of the Tokara Islands ( Baba et al. 1986). Other localities of the species in the East China Sea are 30°03.0’N, 123°35.0’E; 29°26.5’N, 126°32.6’E; 29°19.0’N, 126°44.7’E; 29°02.3’N, 125°47.7’E and 27°14.4’N, 122°23.7’E ( Sekiguchi & Tagawa 1987). Wang (1991) reported the species from Zhejiang (= Chekiang) Province, China, at 29°45’N, 127°E. Huang (1994) and Wang et al. (1998) listed it from Chinese waters. Chan & Yu (1986, 1993) mentioned the species from Taiwan: Ta-Chi, I-Lan County; off NE Taiwan; and the Taiwan Strait. The present material shows that the species is very widely distributed, from the Indian Ocean and Japan to New Caledonia.

HABITAT. — The examined material of this species was found in depths between 53-60 m and 282 m; more than 60% of the lots originated from between 150 and 250 m. The depth records in the literature are 110 m ( Yokoya 1933), 60 m, 100-115 m, 104 m ( Baba et al. 1986), about 150 m ( Chan & Yu 1986), 70 m, 98 m, 102 m, 110 m, 113 m ( Sekiguchi & Tagawa 1987), 106 m ( Wang 1991). Of only two of the examined lots the type of bottom has been indicat- ed, namely mud and muddy sand. Chan & Yu (1993) reported the species from sand and mud.

DESCRIPTION

The body is very heavy and robust, roughened by high tubercles and deep grooves. The carapace is very uneven. The rostrum is small with a broadly rounded tip and is somewhat constricted near the base; dorsally it bears three very small tubercles arranged in a triangle; there is a rostral tooth, which sometimes is very indistinct. The pregastric tooth is absent, in its place the carapace shows a low transverse ridge, slightly curved with the convex side forwards. The gastric tooth is not large and placed rather far forward, sometimes, especially in the older specimens, it is hardly distinguishable from the surrounding tubercles; it is followed by a short median carina and two submedian rows of three tubercles. The whole area between the pregastric ridge and the cervical groove is pitted and eroded. The area before the pregastric ridge is rather even with hardly any tubercles. The cervical groove is wide and deep but is interrupted in the middle by the postrostral carina, which between gastric and cardiac tooth is high and continuous; before the cardiac tooth, namely, there is a curved transverse ridge with four tubercles that joins the median ridge behind the gastric tooth and so effectively closes the cervical groove. In older specimens the cardiac tooth is only slightly higher than the other tubercles, in juveniles it is quite distinct. It is followed by several smaller tubercles that are arranged in longitudinal rows of two to five. The anterior submedian ridge disappears into the eroded area, and is reduced to a single distinct tubercle placed at the level of the gastric tooth. The branchial ridge is widely interrupted by the cervical groove; in the posterior part of the gap a distinct tubercle is visible. The anterior branchial carina is very short because the cervical groove curves far forward; the carina ends in two teeth that are placed on the inner margin of the orbit, behind these, one or two lower teeth or tubercles are visible on the ridge. There are three post-orbital tubercles, the outer is largest, the two inner are small and placed close to the branchial carina. Between the posterior post-rostral and the posterior branchial carina there is a longitudinal row of about four rounded intermediate tubercles of which the anterior are largest. The posterior branchial carina bears two longitudinal rows of seven to nine tubercles; these rows are distinctly curved with the convex side facing outward.The tubercles of the inner row are narrower (sometimes even ridge-like) than those of the outer row. The curvature of these rows of tubercles distinguishes the present species from many others, especially the closely related P. rugosus n. comb. The lateral margin of the carapace has four anterolateral, four mediolateral and about 10 posterolateral teeth, the latter are placed rather irregularly and are of various sizes. The intercervical ridge bears an almost circular conglomerate of about a dozen small tubercles. There are some tubercles between the posterior branchial carina and the posterior lateral margin of the carapace. The ventral surface of the carapace shows many tubercles in the posterior part and is pitted and eroded anteriorly. The marginal groove along the posterior margin of the carapace is rather deep and filled with short hairs. Before the groove is a transverse, rather irregular row of about 20 tubercles, of which two submedian are larger than the rest. Behind the groove there is a more regular row of about 12 tubercles. A short pubescence is present on the carapace between the tubercles. The posterior margin of the carapace shows a blunt rather wide median V-shaped incision.

On the dorsal surface of the first abdominal somite no transverse median groove is present except in the extreme lateral region. However, on the posterior half of the somite there are nine or 10 short longitudinal grooves that, in preserved specimens, show as whitish lines, resembling those of Eduarctus martensii n. comb. The pleura of the first somite end in three blunt teeth, the middle of which is narrow with a rounded top. The posterior margins of somites I and II show a distinct V-shaped median incision, slightly narrower than that of the carapace. In somite III the incision is very small. Somites II to V all have a distinct, but not very high, median dorsal carina, which has the lateral margins lobulate; the cari- nae of somites II and III have a median longitudinal groove. In somite II this groove widens posteriorly so that the two halves of the median carina are diverging. The median carinae of somites IV and V are single and end in a point. The anterior halves of somites II to VI, which disappear under the previous somite when the body is stretched, show no grooves but are somewhat pitted. The posterior half of the tergite of somites II to V do not show the arborescent pattern of very narrow grooves in a smooth surface as found in the genus Scyllarus , but is dominated by a broad and deep, very hairy transverse groove behind which there is a single carina with tubercles and before which there are several groups of tubercles some of which are fused. In the following somites, the posterior transverse carina of the tergite moves farther to the back and becomes less conspicuous, leaving finally only a few scattered tubercles between it and the posterior margin. In these somites the tubercles on the anterior half of the tergite become less distinct than in somite II. The pleura of somites II to IV each show two tuberculate carinae over their full length. The anterior of these ends in the apex of the pleuron, the posterior ends in a blunt tooth on the posterior margin. The anterior margin of pleuron II shows three blunt lobes, each being the end of a short row of one to three small tubercles; the anterior margin of pleuron III shows one or two blunt teeth, that of the pleuron IV has an indistinct tooth or no teeth at all. The posterior margin of pleura II to IV shows the just mentioned blunt tooth, but for the rest the margin is smooth or minutely crenulate. The top of the pleuron is blunt and directed down. In somite V the pleuron has a single tuberculate carina ending in the apex of the pleuron; the anterior margin is convex without teeth, at most with minute crenulations; the posterior margin of the pleuron has two large lobiform teeth. The tergite of the sixth somite has three groups of flattened tubercles in the anterior part; the posterior margin of the tergite carries an irregular row of small tubercles. The telson shows in the central basal part a transverse row of four rather large, but low and blunt tubercles. The four teeth at the end of the firm part of the telson are small and triangular; they are of about equal size and are placed in a transverse line.

The antennular somite shows dorsally a longitudinal median groove; its anterior margin has two broad and bluntly triangular teeth.

The sixth (last) segment of the antenna is relatively short and wide. Its distal margin bears seven slender sharp teeth, of which several usually are broken; in the basal part of the inner margin an indistinct small tooth may be present. The fifth segment has two teeth on the anterior margin, the inner of these is the most slender and is followed by a distinct ridge; the outer tooth is shorter and if a ridge is present it is lower. The anterior margin of the fourth segment has a large tooth at the inner angle, followed outward by three smaller teeth. The upper surface of the segment has a distinct tuberculated oblique carina, which is curved or angled in the middle and ends in the apex of the segment; the basal part of this carina is distinctly higher than the distal part; the change from high to low is rather abrupt and takes place in an angle or curve. Sometimes the carina shows a short side branch. A tubercle may be present to the outside of the base of the main carina, it stands at the articulation with the third antennal segment. The outer margin of the fourth segment has three to five distinct teeth (the apex of the segment excluded); the distal of these are more slender than the proximal. The dorsal surface is rather uneven with a few depressions. The inner margin of the segment has a blunt tooth, and the margin near the articulation with the fifth segment is somewhat elevated.

The upper surface of the epistome is slightly convex. The anterior margin shows a blunt median incision and has at either side a triangular tooth placed near the inner margin of the base of the antenna.

The third maxilliped is implanted some distance dorsad of the anterior margin of the thoracic sternum and thereby somewhat sunken in ventral view.

P.1 is heavier and shorter than the following. The second leg is the longest and the fourth the shortest of the following legs. The dactylus of P.1 is about as long as the propodus, but much narrow- er and regularly tapering; the carpus is slightly shorter than the propodus and more cup-shaped, both have the surface smooth and slightly swollen. There are no hairy fringes on either dactylus, propodus, or carpus. The merus is about as long as carpus and propodus together and has the exposed surface deeply and coarsely pitted and eroded; there is a row of very short hairs on its outer margin; the inner margin is somewhat carinated and is flanked by a wide groove; a tooth with a round- ed top is present on the inner angle of the anterior margin. P.2 has the dactylus about 1.5 times as long as that of the first leg, and as long as the propodus. The carpus is slightly longer than half the propodus. Dactylus, propodus and carpus are smooth and have no hairy fringes. The merus is longer than carpus and propodus together; its outer margin shows an irregular row of rather short hairs. The third leg has the dactylus rather short and wide (about as long as that of the first leg), with rather dense hairy fringes on outer and inner margin and one on the upper surface. The propodus is about 1.5 times as long as the dactylus. It has likewise a fringe of rather long hairs on outer and inner margin and a less distinct one on the upper surface. The carpus is about as long as the dactylus with indistinct fringes of scattered hairs on outer and inner margins and on the exposed surface. It ends in a strong spur-like tooth at the inner anterolateral angle, differing in this respect strongly from the carpi of the first and second leg and from those of other species. The merus is distinctly longer than carpus and propodus together. It bears scattered short hairs. A ridge extends from the inner anterolateral angle posteriorly; the angle is bluntly tooth-shaped. The fourth leg has the dactylus about half as long as the propodus, it bears a dorsal fringe of hairs and a few scattered hairs on the lower edge. The propodus has a fringe of hairs in the distal part of the upper edge and a distal tuft; some scattered hairs are on the rest of the surface. The carpus is slightly less than half as long as the propodus and bears a few scattered hairs; the lower part of its anterior margin bears no spur, but has at the most a short triangular tooth there. The merus is somewhat longer than the propodus; like in the previous leg the lower outer margin shows a ridge that ends in a short rounded tooth. The fifth leg in the female ends in a distinct chela, the dactylus being clearly longer than the fixed finger, it is less than a third of the length of the palm. A fringe of hairs is present on the dorsal margin of the dactylus and is continued on the distal part of the upper margin of the propodus, but is less distinct there. The carpus is slightly more than a third of the length of the propodus; it shows no spur, at most a short triangular tooth like in P.4. The merus is also similar to that of P.4, it is, however, shorter than the propodus.

The thoracic sternum has the anterolateral teeth reaching distinctly beyond the anterior margin proper. This anterior margin shows in the middle a small, rounded U-shaped incision, which is flanked with a small tubercle at each side. The anterolateral teeth carry a longitudinal carina, which in the middle of its length shows a blunt tooth. On each of the sternites a median tubercle is present. The surface of the sternum is closely pitted and eroded. The posterior margin carries a transverse row of tubercles. The lateral parts of the sternum are elevated with blunt ridges and large tubercles.

In the male the pleopods on the second abdominal somite are slender and narrowly elongate; they are widest in the middle and gradually taper to a long, slender tip; the exopod is slightly shorter than the endopod. The next pair of pleopods has the exopod rather short and oval, the endopod is very narrow and somewhat shorter than the exopod. In the following pleopods the exopod is elongate, the endopod is just a short bud.

Size

The examined males had a cl. of 8 to 17 mm, the non-ovigerous females of 7 to 18 mm, the only two ovigerous females examined had cl. 12 and 18 mm; two juveniles measured 5 and 6 mm cl. Baba in Baba et al. (1986: 286) mentioned two ovigerous females with cl. 15.5 and 18.2 mm. Chan & Yu (1986) gave the cl. of an ovigerous female as 15 mm, and that of a non-ovigerous female as 13.5 mm. Chan & Yu (1993: 208) gave the tl. of their specimens as 40 to 70 (mostly 40- 55) mm, which would correspond with cl. about 13 to 23 (mostly 13-18) mm.

Colour

A colour photograph of the male specimen from Lagon Est, east coast of New Caledonia (stn 835) shows a specimen irregularly marbled and spotted with various shades of brown, the tailfan and part of abdominal somite V are much lighter than the rest. But the most conspicuous feature is a dark blue spot over the middle of the first abdominal somite. The margin of the blue spot is not very sharply defined. The specimen from Vanuatu stn CP 1071 is of a darker brown with a few scattered white dots and a white V-shaped line in front of the cardiac tooth. The dark blue spot on the first somite of the abdomen is also quite distinct. The specimen from near Zanzibar was provided with the annotation “Abdomen with bright blue patch”. The coloured photographs of this species provided by Chan & Yu (1986: pl. 9 figs C, D; 1993: 207) also show a dark brown animal marbled with pale brown. The area around the cervical groove is whitish as are also two whitish spots on the posterolateral part of the carapace, and one on the distal part of each of the fourth antennal segments. The first abdominal somite bears the characteristic blue colour on its anterior half. The tailfan is whitish. The eggs are orange. The coloured photograph provided by Baba et al. (1986: 162) shows a dark brown animal slightly marbled. Of the whitish spots only the V-shaped whitish line in front of the cervical groove and the whitish tailfan are distinct, as well as the blue colour on the first abdominal somite.

REMARKS

The species is closely related to P. rugosus n. comb., but can immediately be recognized by curved postero-branchial ridges, the presence of tubercles on the anterior transverse carina of the second abdominal somite, and the presence of a large spur on the carpus of the P.3. It is also close to P. veliger n. sp. (see below).

Figures

FIG. 12. — Petrarctus rugosus (H. Milne Edwards, 1837) n. comb., Gulf of Thailand, carapace length 20 mm (RMNH D 49589); A, dorsal view; B, ventral view; C, lateral view. Photos P. Naiyanetr.

FIG. 13. — Petrarctus rugosus (H. Milne Edwards, 1837) n. comb., Burma, RV Anton Bruun, stn 39A, somites I to III, lateral view; B, thoracic sternum, ventral view; C-G, pereiopods 1 to 5. Scale bar: 2 mm.

FIG. 14. — Petrarctus brevicornis (Holthuis, 1946) n. comb.,New Caledonia;A-F, BATHUS 4, stn CP 952, (MNHN-Pa 1873);A, thoracic sternum;B-D, pereiopods 1 to 3; E, pereiopod 5; F, pereiopod 4; G, LAGON, stn 835, (MNHN-Pa 1279) pereiopod 5. Scale bar:2 mm.

FIG. 67. — A, B, Petrarctus brevicornis (Holthuis, 1946) n. comb.; A, Vanuatu, MUSORSTOM 8, stn CP 1071, carapace length 8 mm (RMNH D 48760), photo J.-L. Menou; B, New Caledonia, Lagon Est, stn 835, carapace length 17 mm (MNHN-Pa 1279), photo J.-L. Menou; C-E, Galearctus timidus (Holthuis, 1960) n. comb.; C, Vanuatu, MUSORSTOM 8, stn CP 1077,, carapace length 17 mm (MNHN-Pa 1851), photo J.-L. Menou; D, E, SW Taiwan, Tong Kong fishing port, 21.X.1995, in dorsal and lateral views, photos T. Y. Chan.