Scalopidia Stimpson 1858
Creators: name: Ng, Peter K. L.
name: Castro, Peter
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Scalopidiidae
Scalopidia

description: Scalopidia Stimpson, 1858
Scalopidia Stimpson, 1858: 95 (type species Scalopidia spinosipes Stimpson, 1858, by monotypy; gender feminine) [ICZN Opinion 85, Direction 37].
Scalopidia. —Miers 1886: 223; Tesch 1918: 224.
Hypophthalmus Richters, in Lenz & Richters, 1881: 429 (type species Hypophthalmus leuchochirus Richters, in Lenz & Richters, 1881, by monotypy; gender masculine; name pre-occupied by Hypophthalmus Cuvier, 1829 [Pisces]).
Diagnosis. Carapace with convex dorsal surface, regions demarcated; cardiac region raised, with low but distinct transverse ridge; front bilobed, with distinct median cleft; anterolateral margin strongly arcuate, granular, without distinct lobes or teeth, not distinctly separated from posterolateral margin. Eye peduncle relatively stout, completely filling orbit, fused to orbit; cornea distinct, partially or completely pigmented. Third maxillipeds relatively short, almost completely covering buccal cavern when closed; ischium rectangular with prominent submedian oblique sulcus; merus quadrate, anteroexternal angle auriculiform; exopod relatively broad, with long flagellum. Chelipeds prominently unequal, heteromorphic in adult males; basis-ischium surface with 2 or 3 short spines; ventral margins of merus lined with short spines; carpus with long sharp tooth on inner dorsal angle; outer surface of chelae smooth or nearly so; major chela: fingers shorter than palm, pollex bent, ventral margin forming prominent concavity with rest of palm, dactylus long, cutting margins with distinct teeth, denticles, sub-basal tooth on dactylus may be enlarged; minor chela: fingers slender, elongated, longer than palm, pollex bent, ventral margin forming prominent concavity with rest of palm, dactylus long, cutting margins with low teeth, denticles. Ambulatory legs proportionally long; anterodorsal margin of each ambulatory coxa with row of 2–4 short spines, ventral surface with 1 or 2 short spines; basis-ischium with 2 or 3 short spines; dorsal, ventral margin of merus with sharp granules and/or spines; dactylus of P5 recurved. Male abdomen slender, somites 4–6 as wide as long; somite 3 as wide as somite 1. G1 sinuous, lateral margins lined with numerous spinules; long simple and/or plumose setae absent. G2 about a third length of G1.
Remarks. Stimpson (1858) described Scalopidia and its type species S. spinosipes from an unspecified number of specimens from Hong Kong. The species was never figured, and no mention or illustrations were given in his posthumous work (Stimpson 1907). Richters (in Lenz & Richters 1881) described a new genus and new species, Hypophthalmus leuchochirus, on the basis of one specimen apparently from Hong Kong as well, and although he discussed and compared it with Xenophthalmus White, 1846 (currently Xenophthalminae Stimpson, 1858: Xenophthalmidae Stimpson, 1858) and Xenophthalmodes Richters, 1880 (currently Xenophthalmodinae Števčić, 2005: Pilumnidae Samouelle, 1819), he was apparently not aware of Stimpson’s (1858) new genus. Miers (1886: 223) first stated that Hypophthalmus Richters, in Lenz & Richters, 1881, is synonymous with Scalopidia Stimpson, 1858, but without any comment. Henderson (1893: 380) agreed and further commented that the “genus Hypophthalmus, Richters (in Lenz and Richters ‘Beitrag zur Krustaceenfauna von Madagascar’), is, as pointed out by Miers, synonymous with Scalopidia, and the H. leucochirus, Richters, apparently differs but little from Stimpson's species [S. spinosipes].” Serène (1964, 1968) recognised S. spinosipes and S. leucochirus as distinct species but without any discussion, and this classification was followed by Ng et al. (2008).
The name Hypophthalmus Richter, in Lenz Richters, 1881, is actually pre-occupied by Hypophthalmus Cuvier, 1829 (usually incorrectly cited as “Agassiz, in Spix & Agassiz 1829”, see Kottelat 1988: 78), a genus of Brazilian fish. Since we are certain that Hypophthalmus Richter, in Lenz Richters, 1881, is a junior synonym of Scalopidia Stimpson, 1858, a replacement name is not necessary.
The three species of Scalopidia recognised can be divided into two groups. One group contains S. spinosipes and S. indica n. sp., and are easily recognised by its well-developed ocular peduncle with a distinct cornea that is only pigmented in the middle portion (Figs. 5 A, B), the strong spinulation on both margins of P2 and P3 meri (relatively weaker but still prominent in the P4 merus) (Figs. 2 C–H, 8A–C), the presence of strong spines on the dorsal margins of the carpi of P3–5 (weakest and/or low in P5, sometimes with small granules or spinules on P2 carpus) (Figs. 2 C–H, 8A–C), strong spines only on the dorsal margin of P2 propodus (Fig. 2 C–H), strong spines on both margins of P3 propodus (Figs. 2 C–H), and the gently recurved P5 dactylus (Fig. 2 C–H). The second group consists of only S. spectabilis n. sp. and is distinguished by having a relatively longer ocular peduncle with the cornea fully pigmented (Fig. 5 C), a relatively weaker and sparser spinulation on both margins of P2–4 meri (only with granules or absent on dorsal margin of P5 merus, ventral margin only with 1 or several short spines or tubercles) (Figs. 2 I, 8D), the dorsal and ventral margins of P2–5 carpus and P2–5 propodus are unarmed (Figs. 2 I, 8D), and a strongly recurved P5 dactylus (Fig. 2 I).
Scalopidia indica n. sp. can also be separated from S. spinosipes n. sp. by the relatively more slender and longer fourth ambulatory merus (Fig. 8 C versus Fig. 8 A, B), relatively wider male abdominal somite 6 (Fig. 10 C versus Fig. 10 A, B), and the distal part of the G1 being relatively longer with a more flared tip (Fig. 12 E, F versus Fig. 12 A, B).
description: Published as part of Ng, Peter K. L. & Castro, Peter, 2013, On the genus Scalopidia Stimpson, 1858 (Crustacea: Brachyura: Goneplacoidea: Scalopidiidae), with the description of one new genus and three new species in Zootaxa 3731 (1), DOI: 10.11646/zootaxa.3731.1.2, http://zenodo.org/record/246527