Crenarctus crenatus ( Whitelegge, 1900 ) Holthuis, 2002

Holthuis, Lipke B., 2002, The Indo-Pacific scyllarine lobsters (Crustacea, Decapoda, Scyllaridae), Zoosystema 24 (3), pp. 499-683 : 659-664

Crenarctus crenatus ( Whitelegge, 1900) n. comb.

( Figs 62 ; 63 )

Arctus crenatus Whitelegge, 1900: 194 , text-fig. 14. Scyllarus crenatus – De Man 1916: 69. — Dakin & Colefax 1940: 173, pl. 2 fig. 1. — Burukovsky 1974: 107; 1983: 150. — Phillips et al. 1980: 69. — Barnett 1989: 123. — McWilliam et al. 1995: 564.

C

Arctus ursus – Haswell 1882: 169 [non Arctus ursus Dana, 1852 = Scyllarus arctus (Linnaeus, 1758) ].

Scyllarus bicuspidatus – Jones & Morgan 1993: 148 [non Crenarctus bicuspidatus ( De Man, 1905) n. comb.].

TYPE MATERIAL. — Syntypes: 2 syntypes, now lost ( AM).

TYPE LOCALITY. — Australia. New South Wales, off Wata Mooli.

MATERIAL EXAMINED. — Australia. South Western Australia. Cathedral Rocks off Rottnest Id, on top of some weed, I.1960, G. Dietmar leg., Western Australian Museum don. (340-64), 1 22 mm ( RMNH D 47797).

Queensland. Thursday Id. 10°35’S, 142°13’E, 1 13 mm ( AM).

New South Wales. Woody Head (= Wooded Bluff), Clarence River mouth, 29°22’S, 153°22’E, 1 foot (= 30 cm) of water below low tide level, under rock, 1.II.1965, A. A. Cameron leg., 1 15 mm (AM P.14930). — Off Minnie Water near Grafton, about 29°41’S, 152°56’E, from crayfish pot, 11 m, X.1966, G. Biddle leg., 1 ov. 22 mm (AM P.15601). — Newcastle, 32°55’S, 151°45’E, from crayfish pot, D. G. Stead, 1 13 mm ( AM). — Off Norah Head, 33°17’S, 151°34’E, trawled, 48-70 m, F. A. McNeill & A. Livingstone, 1 juv. 7 mm (AM P.5355). — Long Bay, coast N of Sydney, reef between tide marks, F. A. McNeill, 1 10 mm (AM P.12130). — Bottle and Glass Rocks, Port Jackson, Sydney, about 33°51’S, 151°15’E, G. P. Whitley, 1 10 mm (AM P.10294). — Off North Head, entrance Port Jackson, Sydney, W. E. J. Paradice, 1 10 mm (AM P.8822). — Off Green Point, Port Jackson, Sydney, dredged in shallow water, CSIRO, 1 juv. 6 mm (AM P.12141). — Near Sow and Pigs, Port Jackson, Sydney, dredged, c. 7 m. F. A. McNeill & M. Ward, 1 10 mm (AM P.9438). — La Perouse, Botany Bay, Sydney, 33°58’S, 151°10’E, J. Douglas leg., 1 juv. 5.5 mm (AM C.1797). — Little Bay near Botany Bay, under damp rock shelf between tide marks, Australian Museum Party, 4 juv. 6-8 mm (AM P.8469). — Coogee, S of Sydney, cavity in wall of Wylie’s Baths, under water, F. A. McNeill, 1 juv. 8 mm ( AM). — Shellharbour, 34°35’S, 150°52’E, between tide marks, 2 ov. 19 and 21 mm (AM P.8440). — Shellharbour, reef between tide marks, 4 10-15 mm (AM P.8441). — Shellharbour, coastal reef between tide marks, 1 13 mm, 1 11 mm (AM P.6855). — Shellharbour, coastal reef between tide marks, G. McAndrew, 1 14 mm (AM P.6765). — Off Wata Mooli, between Port Jackson and Jervis Bay, 34°44’S, 150°39’E, FV Thetis , stn 57, 99-108 m, mud, 22.III.1898, E. R. Waite leg., 2, 1 12 mm, 1 juv. 7 mm. (AM G.2393). — Shoalhaven Bight, 34°53’S, 150°53’E, 27-82 m, RV Endeavour, stn E 282, 1 12 mm ( USNM). — Jervis Bay, 35°05’S, 150°45’E, trawled, CSIRO, 1 9 mm (AM P.12147).

DISTRIBUTION. — The type locality is off Wata Mooli, New South Wales somewhat south of Sydney. The material listed above has been collected at numerous localities along the east coast of Australia from Thursday Island, Queensland (10°35’S, 142°13’E) to Jervis Bay, New South Wales (35°05’S, 150°45’E). Barnett (1989) listed the species from N Queensland. Dakin & Colefax (1940) reported it from New South Wales, and McWilliam et al. (1995) from the Gulf of Carpentaria, Queensland and New South Wales. That the species also occurs in Western Australia is shown by the specimens from Rottnest Island.

HABITAT. — The present material was found from between the tide marks to depths of between 7 and 99- 108 m; it was mentioned from reefs, under a damp rock shelf, from under-water cavities, and from mud. A more intensive study of this species is highly desirable, the more as it does not seem very rare along the E Australian coast.

DESCRIPTION

The rostrum is broadly rounded at the tip and is constricted at the base; dorsally it bears a distinct sharp rostral tooth. The pregastric tooth is welldeveloped and is slightly larger than the rostral tooth. Immediately behind the pregastric tooth there are some small squamiform tubercles, which are arranged in about three longitudinal rows of one to five tubercles; these rows may diverge somewhat posteriorly. The gastric tooth is represented by two submedian tubercles that are situated on the posterior margin of the pregastric tooth, and are somewhat larger than the other tubercles. The cardiac tooth is low and ends in two broad blunt tops, it is slightly larger than the pregastric tooth. Behind the cardiac tooth there are two rows of two to four larger and several smaller tubercles. The posterior submedian carina shows two to four larger and a few smaller tubercles, the anterior being very strong, almost as strong as the cardiac tooth, with which these teeth lie in almost a single transverse line. The anterior submedian carina bears two or three larger and one to three smaller tubercles, here too the anterior tubercle is largest and pointed. The branchial carina is divided in two by the deep and rather wide cervical groove; there is no tubercle in the gap. The anterior branchial carina ends in the inner margin of the orbit, where it has the two usual teeth. Behind the posterior of this pair

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there are three smaller, but still distinct tubercles on the anterior branchial carina. A row of small and indistinct tubercles runs behind and parallel to the posterior orbital margin. Between this row and the anterior branchial carina sometimes a second row of very small tubercles may be seen. The posterior branchial carina ends anteriorly in a strong pointed tooth, behind which it bears a double row of about eight to 10 large squamiform tubercles. The intermediate row consists of four tubercles; between this intermediate row and the posterior branchial carina a rather large tubercle is present. The lateral margin of the carapace bears four to six anterolateral, three mediolateral and 10 to 12 posterolateral teeth. The intercervical ridge bears about six to eight irregularly arranged tubercles. The marginal groove along the posterior margin of the carapace is rather narrow and deep; before and behind it there is a double, in some places treble, row of tubercles. On either side of the median carina of the carapace one of the tubercles before the marginal groove is distinctly larger than the rest. The posterior margin of the carapace bears a wide and shallow triangular median incision.

The first abdominal somite has an uninterrupted and distinct transverse groove. Before this groove the surface of the somite is smooth, behind it are about 30 longitudinal short grooves, some of which may show side grooves in their distal part. The abdomen has no dorso-median ridge. The surface of the posterior halves of somites II to V have the usual arborescent pattern of narow and deep grooves; the dorsomedian figure has the lateral margins deeply incised, being thereby lobulated. This dorsomedian figure of somite II is elevated anteriorly and ends in a blunt lobe. The posterior margins of somites II to IV show a median incision, which lacks in somites V and VI. The anterior half of somites II to V shows a reticular pattern of very shallow grooves. The pleura of the first abdominal somite have the lateral margin bilobate, the anterior lobe has its margin incised. The surface of the pleura has tubercles, which on the anterior pleura are smaller and more distinct than on the more posterior. The tips of he pleura II and III are more triangu- lar, the posterior bluntly rounded; they do not have a sharp tooth. The four teeth at the end of the solid part of the telson are sharp and of about the same length.

The anterior margin of the antennular somite bears four teeth in each half; all of these are triangular, the inner are broadest, the outer are in contact with the third antennal segment.

The distal margin of the last (sixth) segment of the antenna is convex and bears six elongate teeth, which gradually taper towards the rather narrowly rounded apex. The spaces between the teeth are narrowly triangular but distinct; the inner margin of the segment bears a single small tooth. The antero-internal angle of the fifth antennal segment bears a sharp tooth, which carries a dorsal carina on which a low tooth is visible. The anterior margin of the fourth antennal segment bears four or five teeth, the second from the inner margin being largest; all teeth are sharply triangular. The outer margin of the fourth segment bears two large teeth (the apical tooth not included), while sometimes a small additional third tooth is present at the base of the apical tooth. The upper surface of the segment bears a single sharp median carina.

The anterior margin of the epistome shows a rather deep median triangular incision, the top of which may be either sharp or blunt. On either side of the incision the margin is convex and ends laterally in a triangular tooth.

P.1 is far more robust than P.2. The merus bears a distinct curved groove in the upper part of the outer surface and a straight groove in the lower part; both grooves are filled with short hairs. The carpus shows some short hairy grooves in the upper outer part, while the propodus has a longitudinal hairy groove there. The dactylus of P.2 is slightly longer than that of P.1, and much longer than that of P.3; it is almost twice as long as that of P.4; the dactylus of P.5 is the shortest of all. None of the dactyli shows a hairy fringe: those of P.1 and P.2 are totally naked, while the others have an extremely short pubescence in the basal part. The propodus and carpus of P.2 are entirely naked and without grooves. The propodus of P.3, but not of the other legs has a heavy dorsal fringe of hairs; this propodus is somewhat broader than those of P.2 and P.4, but not broader than the merus of P.3; its outer surface has two distinct longitudinal hairy grooves. Two such grooves are also found in the propodus of P.4 and one on that of P.5. The carpus of P.3 and P.4, but not that of P.5, have a dorsal fringe of hairs (those of P.4 being shorter than the ones of P.3). The outer surface of the carpus of P.3 to P.5 shows a longitudinal hairy groove. The merus of P.2 to P.5 bears a dorsal fringe of hair. The outer surface of the merus of P.2 to P.4 has two, that of P.5 one hairy groove. A ventral hairy groove is present on the merus of P.3 to P.5.

The anterior margin of the sternum is shallowly U-shaped with a triangular incision in the middle. The two anterolateral teeth are rather short and blunt; the submedian tubercles are distinct, in smaller specimens they are far more distinctly pronounced than in larger specimens. Obliquely behind the anterolateral teeth the ventral surface of the sternum shows two flattened teeth which are situated closer to each other than to the anterolateral teeth. A median tubercle, sometimes rather distinct, is visible on the fifth sternite, it is rather short and wide, being antero-posteriorly somewhat compressed. Near the bases of the legs the sternum shows a squamiform sculpturation. The posterior margin of the fifth sternite is smooth.

The first pleopods of the male, placed on the second abdominal somite, are normal in shape with the endo- and exopod well-developed. In the following pleopods the exopod is rather distinct and foliaceous, the endopod being reduced to a mere bud.

Colour

In some of the preserved specimens a dark circular spot can be seen in the middle of the first abdominal somite. The body is somewhat mottled. A dark spot may be seen in the outer basal angle of the fourth antennal segment. Dark bands have been noted over the middle of merus and carpus and over the basal half of the propodus of P.2 to P.5.

Size

In the examined material males had cl. 10 to 15 mm, non-ovigerous females had cl. 10 to 14 mm and ovigerous females had cl. 19-22 mm; juveniles had the carapace 6 to 9 mm long.

REMARKS

It seems most likely that the specimen of the present species from Thursday Island present in the collection of the Australian Museum is the one reported upon by Haswell (1882) under the name Arctus ursus from that locality. Arctus ursus Dana, 1852 is a junior synonym of Scyllarus arctus (Linnaeus, 1758) , a species from the NE Atlantic. De Man (1916) and Balss (1921) thought it is possible that Haswell’s specimen could be Scyllarus sordidus Stimpson, 1860 (= Biarctus sordidus n. comb.) (see also there). It seems most likely that it actually is C. crenatus n. comb., certainly when the present Thursday Island specimen is the one seen by Haswell.

Whitelegge’s two type specimens were evidently juveniles. The original description fits juveniles of the present species, while adult topotypic material belongs certainly to it. Therefore I have no hesitation to assign the name crenatus to this species. The specimens from Rottnest Island, which I had at first identified as Scyllarus bicuspidatus , and as such were mentioned by Jones & Morgan (1993), upon a subsequent re-examination proved to belong to C. crenatus n. comb.

Figures

FIG. 62. — Crenarctus crenatus (Whitelegge, 1900) n. comb., Australia, New South Wales, off Minnie Water near Grafton, ovigerous carapace length 22 mm (AM P.15601); A, dorsal view; B, lateral view; C, thoracic sternum.

FIG. 63. — Crenarctus crenatus (Whitelegge, 1900) n. comb., Cathedral Rocks, Rottnest Island, W Australia, carapace length 22 mm (RMNH D 47797); A-E, pereiopods 1 to 5. Scale bar: 1 mm.