Notonyx gigacarcinicus, Clark & Ng, 2006
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publication ID |
https://doi.org/ 10.5281/zenodo.5395837 |
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persistent identifier |
https://treatment.plazi.org/id/052EE325-FFD6-3478-FCEA-FE1AFDF4FA9B |
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treatment provided by |
Marcus |
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scientific name |
Notonyx gigacarcinicus |
| status |
sp. nov. |
Notonyx gigacarcinicus View in CoL n. sp.
( Figs 4 View FIG ; 5 View FIG ; 6B View FIG ; 7 View FIG )
TYPE MATERIAL. — Thailand. Phuket, Ao Tang Khen Bay , in reef rubble, V.2000, coll. Paul Clark and Peter Ng, ♂ holotype 12.1 × 8.7 mm ; 1 ♀ paratype 13.8 × 9.9 mm ( ZRC 2000.0981 View Materials ) .
TYPE LOCALITY. — Ao Tang Khen Bay, Phuket, Thailand.
ETYMOLOGY. — Giant, from the Oxford Dictionary a person of extraordinary ability; carcinology, the study of Crustacea. Named in recognition of the immense contribution made by Pat McLaughlin to the study of Crustacea. The specific name gigacarcinicus is a compound adjective derived from the Greek gigas and carcinos. Gender masculine.
DESCRIPTION
Holotype male: carapace subquadrilateral, length about 3/4 width, frontal marginal straight, just over 1/3 width. Anterolateral margin short but entire, curved, without teeth; posterolateral margin longer. Dorsal surface of carapace smooth, without indication of regions except for shallow impression in gastric region; dorsal surface convex anteriorly and posteriorly.
Antennules relatively long with terminal setae reaching cornea of eye. Basal antennal joint relatively small, short, positioned orbital hiatus. Cornea of eye small.
Gape present between third maxillipeds when closed; merus slightly shorter than ischium. Anterior and outer (external) margin of merus forms a right angle.
Chelipeds subequal, with distinct keel on ventral margin of fixed finger. Dorsal margin of propodus smooth, devoid of denticles. Inner margin of carpus rounded, without acute tooth or spine.
Pereiopods smooth, unarmed with some scattered setae.
A
C
Thoracic sternum relatively broad; surface lightly pitted. Sternites 1 and 2 completely fused, separated from sternite 3 by distinct transverse suture. Sternites 3 and 4 fused except for lateral incision marking somites.
Male abdomen with third somite distinctly broader than second and fourth. First and second pleopods as figured.
Colour
In life ( Fig. 7 View FIG ), cream overall with two prominent longitudinal maroon stripes on the dorsal surface between the protogastric and hepatic regions of the carapace. There is also a maroon spot on the cardiac region, and the posterolateral part of the branchial regions are similarly coloured.
REMARKS
Notonyx gigacarcinicus n. sp. differs from N. nitidus s.s., in several key aspects: the acute spine on the inner margin of the cheliped carpus is absent, forming instead a relatively smooth and curved margin ( Fig. 3C View FIG vs. Fig. 4E View FIG ), the merus and ischium are subequal in length ( Fig. 5E, F View FIG ) (vs. the ischium distinctly longer, Fig. 3C, D View FIG ), the telson of the male abdomen is distinctly more triangular ( Fig. 5H View FIG ) (vs. basally broader with the sides somewhat convex, Fig. 3F View FIG ), the ambulatory meri are proportionately
A new species of Notonyx from Thailand stouter ( Figs 3E View FIG ; 5G View FIG ), the tip of the G2 is hooked downwards ( Fig. 5I View FIG ) (vs. directed laterally, Fig. 3G View FIG ), and most significantly, the G1 is relatively much stouter, with the subdistal ventral part prominently swollen ( Fig. 5J, K View FIG ) (vs. the entire G1 more slender and evenly cylindrical, Fig. 3H, I View FIG ). In the form of the swollen distal part of the G1, N. gigacarcinicus n. sp. resembles the specimens from the Philippines, and to some degree, the Lesser Sunda Islands which had been identified to “ N. nitidus ” (possibly incorrectly as discussed above). However, the G1 of N. gigacarcinicus n. sp. is not only relatively much stouter, the distal part is not elongated, curved or hooked, and the subdistal ventral swelling is far more strongly developed. In addition, the ischium of the third maxilliped of the Philippines specimen (cf. Serène & Umali 1972: fig. 90) is distinctly longer than the merus, whilst in N. gigacarcinicus n. sp., the two segments are subequal in length ( Fig. 5C View FIG ). The male telson of the Philippines specimen, as figured by Serène & Umali (1972: fig. 91) is also markedly more broadly triangular than that of N. gigacarcinicus n. sp. ( Fig. 5H View FIG ). In contrast to the down-turned tip of the G2 of N. gigacarcinicus n. sp., that of the Lesser Sunda Islands specimen is upturned ( Stephensen 1946: fig. 47B). The G2 of the Philippines specimen ( Serène & Umali 1972: figs 94, 95), however, agrees well with N. gigacarcinicus n. sp. All indications are that N. gigacarcinicus n. sp. is not conspecific with the specimens from the Lesser Sunda Islands and Philippines.
The life colour of N. gigacarcinicus n. sp. differs markedly from that described or reported for N. nitidus . The type of N. nitidus was described as rosy with stripes (A. Milne-Edwards 1873), and the topotypes appear to be spotted. Notonyx gigacarcinicus n. sp. is creamy white with just two prominent longitudinal maroon stripes across the median part of the carapace, with the cardiac region and posterolateral part of the branchial regions also similarly coloured ( Fig. 7 View FIG ).
The new species differs markedly from N. vitreus , in that the carapace is proportionately broader transversely (vs. more squarish), the male telson is triangular (vs. more semicircular), the subdistal ventral part is prominently swollen ( Fig. 5J, K View FIG ) (vs. evenly cylindrical) and the tip of the G2 is hooked downwards (vs. prominently upturned) (cf. Alcock 1900: 319; Alcock & McArdle 1903: pl. 61, fig. 3; Tesch 1918: 221; Serène & Soh 1976: fig. 16).
A statement must be made regarding the male specimen of N. vitreus reported by Takeda (1989) from a depth of 45 m at Oshima Passage in Japan. It is not the species of Alcock (1900). In his report, Takeda (1989: 170, fig. 15C) commented that while his specimen had a proportionately narrower carapace, it did possess a spine on the inner margin of the carpus of the cheliped unlike the type and previous descriptions. The G1 structure figured by Takeda (1989: fig. 15F-H) also differs markedly from that figured by Serène & Soh (1976: fig. 16A-C), being straighter, stouter and having the distal section dilated. While Takeda’s (1989) specimen is somewhat larger than that of Serène & Soh (1976) (4.8 × 3.9 mm vs. 4.0 × 3.2 mm), the differences observed are still significant, especially since Serène & Soh (1976) also concurred that the carpus of the cheliped of their specimens were unarmed.It thus seems unlikely that the specimen of Takeda is N. vitreus . Further, Takeda (1989) did not cite the paper of Serène & Soh (1976) in his bibliography, which suggests he was not aware of their record from western Thailand.
ECOLOGICAL NOTES
The specimens of N. gigacarcinicus n. sp. were under a large coral rock atop rubble in the lower tidal zone. The specimens were not under the rock per se but dwelled 18-22 cm deeper in the rubble. This habitat is hardly ever collected, difficult to sample ( Dennis & Aldhous 2004), and has already yielded some interesting brachyuran finds in recent years (e.g., Ng 2002a, b; Ng & Takeda 2003; Tan & Ng 2003; Ng & Ng 2003). It is noteworthy that all previous specimens of other Notonyx species have been collected in deeper subtidal waters with dredges that are unable to scrape deep into rubble substrates.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.