Hephthopelta occidentalis, Ng, Peter K. L. & Castro, Peter, 2016

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182 : 53-55

publication ID	https://doi.org/ 10.11646/zootaxa.4209.1.1
publication LSID	lsid:zoobank.org:pub:849BAB5C-464A-4B4A-A586-5742411EDC01
DOI	https://doi.org/10.5281/zenodo.5617127
persistent identifier	https://treatment.plazi.org/id/F16BFB33-FF97-FFCD-FF6A-F9D8FC7FFC8E
treatment provided by	Plazi
scientific name	Hephthopelta occidentalis
status	sp. nov.

Treatment

Hephthopelta occidentalis View in CoL n. sp.

( Figs. 10 View FIGURE 10 I, J; 24B; 31C; 40G, H; 52B, C; 59C; 72)

Type material. Holotype male (6.1 × 6.6 mm, with sacculinid) (MNHN-IU-2010-1031), Madagascar, along Mahajamba Bay , MIRIKI, stn CP3249, 14°48’S, 47°00’E, 620‒637 m. GoogleMaps

Paratypes: 1 male (4.7 × 4.9 mm) ( ZRC 2015.247 View Materials , ex-MNHN-IU-2010-1284), between Majunga and Cape Saint-André, MIRIKI, stn CP3279, 15°22’S, 45°57’E, 780‒1020 m, 12.07.2009. GoogleMaps

Diagnosis. Carapace ( Fig. 10 View FIGURE 10 I, J) subtrapezoidal, globose, slightly wider than long; front bilobed, with shallow to well-defined median cleft; anterolateral margins arcuate, minutely granular, without distinct lobes or teeth. Orbits ( Fig. 24 View FIGURE 24 B) short, eye peduncle filling orbit, short, immobile; cornea reduced, with prominent spot of black pigment. Posterior margin of epistome ( Fig. 24 View FIGURE 24 B) with broadly triangular median lobe, deep median fissure, lateral margins semicircular. Third maxilliped ( Fig. 31 View FIGURE 31 C) merus ovate, ischium slightly elongated, slightly longer than merus. Proportionally long ambulatory legs ( Fig. 10 View FIGURE 10 I), folded P5 merus almost reaching anterior margin; P5 merus 0.8 cl. Meri of P2, P3 with short teeth, meri of other ambulatory legs with microscopic granules, unarmed.

Chelipeds ( Figs. 10 View FIGURE 10 I, J; 40G, H) subequal in length, slightly dissimilar in female, heteromorphic in males; fingers of minor chela ( Fig. 40 View FIGURE 40 H) flattened laterally, broad throughout most of length, shear-like, cutting margins with low, broad teeth. Ventral surface of cheliped merus with 3 teeth (additional smaller teeth or large tubercle) on outer margin, inner margin unarmed. Inner margin of carpi with long distal tooth ( Fig. 10 View FIGURE 10 I, J). Fused thoracic sternites 1, 2 ( Fig. 52 View FIGURE 52 B) transversely narrow, high; fused thoracic sternites 3, 4 ( Fig. 52 View FIGURE 52 B); transversely narrow. Pleon of holotype parasitized by sacculinid ( Fig. 52 View FIGURE 52 C). G1 ( Fig. 72 View FIGURE 72 A–C) stout, distal part straight with spinules. G2 ( Fig. 72 View FIGURE 72 D) longer than G1, straight, slender, distal segment directed inwards, almost as long as basal segment. Female unknown.

Etymology. The epithet occidentalis refers to geographical distribution of the new species, which is so far restricted to the Western Indian Ocean.

Remarks. Although only two specimens of H. occidentalis n. sp. are available, they possess several characters that separate them from H. lugubris . Hephthopelta occidentalis can be separated by the posterior margin of the epistome being broadly triangular ( Fig. 24 View FIGURE 24 B) (posterior margin of epistome is truncate in H. lugubris , Fig. 24 View FIGURE 24 A), the ambulatory meri are relatively longer ( Fig. 10 View FIGURE 10 I) (meri are relatively shorter in specimens of H. lugubris of comparable size; Fig. 10 View FIGURE 10 D–H), the ischium and merus of the third maxilliped are proportionately longer ( Fig. 31 View FIGURE 31 C) (ischium and merus proportionately shorter and more quadrate in specimens of H. lugubris of comparable size; Fig. 31 View FIGURE 31 A, B), and the cornea of the eye has a prominent spot of black pigment ( Fig. 24 View FIGURE 24 B) (cornea with only a faint trace of black pigmentation in H. lugubris , Fig. 24 View FIGURE 24 A).

The G1 of H. occidentalis appears to be relatively shorter and stouter ( Fig. 72 View FIGURE 72 A) than that of H. lugubris ( Fig. 71 View FIGURE 71 A, B, F, G, J). A smaller specimen of H. lugubris from Fiji (6.3 × 6.5 mm, MNHN-IU-2013-9028), however, also has a relatively short G1 ( Fig. 71 View FIGURE 71 K, L), suggesting the distal part elongates in larger specimens. While the tip of the G 1 in H. occidentalis is directed obliquely laterally ( Fig. 72 View FIGURE 72 A–C), however, that of H. lugubris is still gently curved upwards ( Fig. 71 View FIGURE 71 K, L). In any case, the G1 appears to vary slightly in H. lugubris , a smaller specimen from Solomon Is. (7.3 × 7.8 mm, MNHN-IU-2013-9037) has a more rounded carapace but with a G 1 in which the distal part is elongated and gently curved upwards, but has the basal part relatively more slender than that of larger males ( Fig. 71 View FIGURE 71 J versus Fig. 71 View FIGURE 71 F, G).