Notonyx A. Milne-Edwards, 1873

Clark, Paul F. & Ng, Peter K. L., 2006, A new species of Notonyx A. Milne-Edwards, 1873 (Crustacea, Brachyura, Goneplacidae) from the intertidal zone of Phuket, Thailand, Zoosystema 28 (2), pp. 539-551 : 540-544

Genus Notonyx A. Milne-Edwards, 1873

REMARKS

While Notonyx A. Milne-Edwards, 1873 has traditionally been classified in the Goneplacidae , its subfamilial position remains uncertain. In his discussion on the taxonomy of the Goneplacidae, Serène (1964a , b) did not consider the genus. Later Serène (1968: 91) referred Notonyx to the Rhizopinae Stimpson, 1858, which at that time was regarded as a subfamily of the Goneplacidae . In later works, Notonyx was assigned without comment to the Goneplacinae ( Serène & Umali 1972; Serène & Soh 1976). In her synopsis of xanthoids and selected goneplacids, Guinot (1971) did not

A new species of Notonyx from Thailand consider Notonyx . Ng (1987), removed the Rhizopinae from the Goneplacidae , and transferred it to the Pilumnidae . He commented that Notonyx was neither a rhizopine nor a pilumnid, and that the systematic position of the genus required review. In a recent major study of the phylogeny and classification of the Goneplacidae ( Karasawa & Kato 2003) , the systematic status of Notonyx was not discussed.

The male abdominal and gonopod characters of Notonyx species suggest that the genus should be assigned to the Goneplacinae as presently defined. All the male abdominal segments are free and mobile, the G1 is relatively stout and armed with distinct short spines, and the G2 is prominently longer than the G1 with the distal part elongate. The quadrate carapace and smooth outline of Notonyx species , however, is atypical in form from other goneplacines, but this feature must be considered as less phylogenetically significant than the male abdominal and gonopodal structures.

Notonyx nitidus A. Milne-Edwards, 1873 ( Figs 1-3 ; 6A )

Notonyx nitidus A. Milne-Edwards, 1873: 269 , pl. 12, fig. 3. — Miers 1886: 236. — Alcock 1900: 319. — Tesch 1918: 219. — Balss 1938: 74. —? Stephensen 1946: 172, fig. 47A, B. —? Serène & Umali 1972: 82, figs 90-95. — Serène & Soh 1976: fig. 16E.

Non Ceratoplax laevis Miers, 1884: 244 , pl. 25, fig. C. — Lanchester 1900: 751. — Tesch 1918: 203. — Stephensen 1946: 172. — Balss 1938: 74. Valid name as Pronotonyx laevis ( Miers, 1884) , see Ward 1936: 2 and Ng 1987: 98.

TYPE MATERIAL. — New Caledonia. Coll. M. Balansa, ♀ holotype 9.2 × 6.6 mm ( MNHN-B 10220).

TYPE LOCALITY. — New Caledonia.

MATERIAL EXAMINED. — New Caledonia. LAGON, stn 116, île Ouen, baie du Prony, 22°26’S, 166°42’E, 43 m, 22.VIII.1984, coll. Bertrand Richer de Forges , 1 ♀ 7.4 × 5.3 mm ( MNHN-B 29885 ). — Stn 131, île Ouen, baie du Prony, 22°28’S, 166°50’E, 38 m, 23.VIII.1984, 1 ♂ 6.2 × 4.5 mm ; 1 ♀ damaged ( MNHN-B 29886 ). — Stn 150, île Ouen, baie du Prony, 22°30’S, 166°50’E, 62- 68 m, 24.VIII.1984, 1 ♀ 7.0 × 5.7 mm ( MNHN-B 29887 ). — Stn 247, île Ouen, baie du Prony, 22°24’S, 166°51’E, 43 m, 24.X.1984, 2 ♂♂ 5.8 × 4.5-6.5 × 4.9 mm ( MNHN-B 29888 ). — Stn 322, Grand Récif Sud, 22°30’S, 166°58’E, 71 m, 27.XI.1984, 1 ♂ 7.0 × 5.4 mm ; 1 ♀ 7.7 × 5.8 mm ( ZRC 2005.0139 ).— Stn 326, Grand Récif Sud, 22°26’S, 167°02’E, 67 m, 28.XI.1984, 1 ♀ 6.3 × 5.1 mm ( MNHN-B 29889 ). — Stn 355, Grand Récif Sud, 22°30’S, 167°04’E, 82 m, 29.XI.1984, 1 ♀ 6.2 × 4.9 mm ( MNHN-B 29890 ). — Stn 615, 22°06.7’S, 166°57.0’E, 56-60 m, 5.VIII.1986, 1 ♀ 7.0 × 5.3 mm ( MNHN-B 29891 ). — Stn 684, 21°37.2’S, 166°16.7’E, 30-31m, 9.VIII.1986, 1 ♀ 6.8 × 5.2 mm ( MNHN-B 29892 ). — Stn 875, 20°36.7’S, 164°52.2’E, 21 m, 13.I.1987, 1 ♂ 4.3 × 3.0 mm ; 1 ovig. ♀ 5.4 × 3.8 mm ( MNHN-B 29893 ). — LAGON, stn DW 1235, 22°24.08’S, 166°55.44’E, 51 m, 9.III.1993, coll. Robert Leborgne 5 ♂♂ 5.4 × 4.2-6.7 × 5.1 mm ; 4 ♀♀ (2 ovig.) 6.3 × 4.9-6.8 × 5.0 mm ( MNHN-B 29894 ) .

MUSORSTOM 4, stn 232, 22°28.8’S, 167°04.7’E, 77 m, 1.X.1985, coll. Bertrand Richer de Forges, 1 juv. 4.8 × 3.9 mm ( MNHN-B 29895).

Chesterfield Islands. CORAIL 2, stn DW 154, 19°52.04’S, 158°26.50’E, 35 m, coll. Bertrand Richer de Forges , 1.VIII.1988, 1 juv. 4.5 × 3.6 mm ( MNHN-B 29896 ). New Guinea. HMS Challenger, stn 188, 9°59’0”S, 139°42’0”E, South of New Guinea, 51 m, 10.VIII.1874, det. E. J. Miers, pres. Lords of the Admiralty, 1 ♂ 8.0 × 5.1 mm ; 1 ♀ 8.5 × 6.7 mm ( NHM 1884.31 ) .

Timor Sea. Holothuria Bank, 13°35’S, 126°E, 71 m, coll. P. Bassett Smith, HMS Penguin , pres. Lords of the Admiralty, 1 ♂ 6.1 × 4.7 mm; 1 ♀ 6.1 × 4.6 mm (NHM 1892.3.26.125-126).

DEPTH RANGE. — 13 m ( Tesch 1918) to 82 m (LAGON, stn 355).

REMARKS

Notonyx nitidus was described from a female collected in New Caledonia and illustrated with a small, schematic figure (A. Milne-Edwards 1873: pl. 12, fig. 3). The male gonopods were unknown until Stephensen (1946: fig. 47A, B) from the Lesser Sunda Islands, and Serène & Umali (1972: figs 92-95) from the Philippines, illustrated the morphology. However, the meticulous collecting of IRD has made available a number of males from New Caledonia, and the gonopods of one of these (ZRC 2005.0139) are figured here ( Fig. 4M, N ). Interestingly, the gonopods figured by Stephensen (1946: fig. 47A, B) and Serène & Umali (1972: figs 92-95) do not agree with those in specimens from New Caledonia. Serène & Umali (1972: figs 92-95) stated that the male gonopod is from a male 9.0 × 7.0 mm, but this is incorrect as these are the measurements of the holotype female as documented by A. Milne-Edwards (1873: 269, pl. 12, fig. 3). Serène & Soh (1976: 19) subsequently corrected this when they figured the carapace of the Philippines specimen and stated that it actually measured 7.5 × 5.0 mm.

The gonopods of the specimens from New Caledonia ( Fig. 2 ), Philippines ( Serène & Umali 1972: figs 92-95) and Lesser Sunda Islands ( Stephensen 1946: fig. 47A, B), differ markedly and cast doubt on whether all are conspecific. The New Caledonian specimen figured here is topotypic and the G1 shows a simple, slender tube with the distal part gently curving inwards. The G1 of the Philippines specimen (7.5 × 5.0 mm) is more prominently curved distally but has the tip bifurcated, and there is a swelling on the subdistal ventral margin. The Lesser Sunda Islands specimen (10.0 × 7.0 mm) has a G1 which resembles that of the Philippines male, but the distal part is even more strongly curved, appearing hook-like, and there is only a slight subdistal ventral swelling. As the male from the Lesser Sunda Islands is larger than that from the Philippines, it is possible that the differences are ontogenetic. The difference in size of the subdistal ventral swelling can easily be accounted for by the G1s being drawn from slightly different orientations. However, the tips of the distal segment of the G2 also differ, with the Lesser Sunda Islands specimen having the tip twisted upwards ( Stephensen 1946: fig. 47B) while that from Philippines has the tip bent downwards like a hook ( Serène & Umali 1972: figs 94, 95). Considering the distance between these two localities, it is possible that the Philippines and Lesser Sunda Islands specimens belong to separate species.

The largest New Caledonian male examined during the present study (7.0 × 5.4 mm, ZRC 2005.0139) is similar in size to the Philippines specimen (7.5 × 5.0 mm), so that the differences in the G1 cannot be explained by size differences. It appears that the Philippines and Lesser Sunda Islands specimens (regardless of whether they are conspecific) are not N. nitidus s.s. They are also not the new species described here, differing in a number of characters and their identities will need to be resolved when the specimens can be re-examined.

Alphonse Milne-Edwards (1873) described and figured the dorsal margin of the propodus of the chela of N. nitidus as possessing denticles but these structures were not observed in the material studied, including the type female ( Fig. 1 ). The surface of the larger specimens has the surface somewhat more uneven and gently pitted but is certainly not denticulate. What is apparent is a row of low, somewhat longitudinal granules on the outer surface of the dactylus ( Fig. 5A ).

Tesch (1918: 220) noted that according to A. Milne-Edwards (1873), N. nitidus was a “rosy colour with longitudinal and oblique reddish stripes” while his specimens from Indonesia were “ivory white”. Alphonse Milne-Edwards (1873: 269) described his female in detail when the colour was fresh as: “Sa couleur est rosée avec des bandes rougeâtres, disposées régulièrement: l’une occupe la ligne médiane de la région cardiaque et se bifurque en avant pour en rejoindre deux qui bordent la région gastrique; chacune de celles-ci se relie à une autre bande oblique qui se détache du bord latéral, en arrière de l’insertion des pattes antérieures”. In the New Caledonia specimens examined, most of their colour was faded, and although it is still possible to discern numerous small spots on the carapace, this is insufficient to confirm any colour patterns.

The male and female (NHM 1884.31) from south of New Guinea are considered to be Notonyx nitidus s.s. They are larger than the New Caledonian material examined, and the G1 looks identical, except that the median part is slightly more swollen. In the specimen figured, the median part of the G1 has a slight dilation ( Fig. 2I ) and in this larger male from New Guinea, it is slightly more swollen. But this is not to the extent or shape of the new species described here. Also, the male abdomen is somewhat broader than the smaller male from New Caledonia (cf. Fig. 2F ), with the lateral margins of segments 5 and 6 much less concave and appearing almost straight. This is interpreted as a size-related difference. The form of the carpus of the cheliped and third maxilliped are identical with the New Caledonian material.

The two specimens from Holothuria Bank (NHM 1892.3.26.125-126) are here regarded as N. nitidus s.s., even though they are from northwestern Australia, and relatively close to the Lesser Sunda Islands. The G1 of the male specimen is similar to those from New Caledonia except that the distal quarter is slightly more elongate and curved, but considered within the variation for the species. However, the pleopod is different from those illustrated by Stephensen (1946) from the Lesser Sunda Islands, which has the subdistal part swollen and the distal part distinctly hooked towards the mid line of the crab.

The only record of Notonyx nitidus from the Persian Gulf is by Alcock (1910: 319), which is based on a specimen 11 × 8.5 mm in size. This specimen, presumably in the Zoological Survey of India (Calcutta), will need to be re-examined to ascertain its identity.

Figures

FIG. 1. — Notonyx nitidus A. Milne-Edwards, 1873, holotype ♀ 9.2 × 6.6 mm (MNHN-B 10220), New Caledonia, coll. M. Balansa.

FIG. 2. — Notonyx nitidus A. Milne-Edwards, 1873, ♂ topotypic 7.0 × 5.4 mm, New Caledonia (ZRC 2005.0139), carapace: A, dorsal view; B, ventral view; C, frontal view.

FIG. 3. — Notonyx nitidus A. Milne-Edwards, 1873, ♂ topotypic 7.0 × 5.4 mm, New Caledonia (ZRC 2005.0139): A, dorsal view of carapace; B, third maxilliped; C, carpus of left cheliped; D, ischium of left cheliped; E, right fifth pereiopod, setae denuded; F, male abdomen; G, left second male gonopod; H, left first male gonopod; I, distal end of left first male gonopod.Scale bars:A, C-H,1.0 mm; B, I, 0.5 mm.

FIG. 6. — Outer surface of right chela: A, Notonyx nitidus A. Milne-Edwards, 1873, ♂ topotypic 7.0 × 5.4 mm, New Caledonia (ZRC 2005.0139); B, Notonyx gigacarcinicus n. sp., holotype ♂ 12.1 × 8.7 mm, Thailand (ZRC 2000.0981).

FIG. 4. — Notonyx gigacarcinicus n. sp., holotype ♂ 12.1 × 8.7 mm, Thailand (ZRC 2000.0981), carapace: A, dorsal view; B, ventral view; C, frontal view.

FIG. 5. — Notonyx gigacarcinicus n. sp., holotype ♂ 12.1 × 8.7 mm, Thailand (ZRC 2000.0981): A, dorsal view of carapace; B, frontal view including antenna; C, third maxilliped; D, sternal segments 1-3; E, carpus of left cheliped; F, ischium of left cheliped; G, right fifth pereiopod, setae denuded; H, male abdomen; I, left second male gonopod; J, left first male gonopod; K, distal end of left first male gonopod. Scale bars: A-J, 1.0 mm; K, 0.5 mm.