Parapleisticantha Yokoya 1933
Creators: name: Ng, Peter K. L.
name: Forges, Bertrand Richer De
name: Lee, Bee Yan
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Oregoniidae
Parapleisticantha

description: Parapleisticantha aie n. sp.
(Figs. 1D, 14–18)
Type material. Holotype: male (cl 18.7 mm, pcl 16.5 mm, cw 12.4 mm, pcw 11.5 mm) (MNHN-IU-2014-18677a), stn CP 4502, New Ireland, 02°32’S 150°44’E, 193–206 m, coll. N.O. Alis, KAVIENG 2014 expedition, 7 September 2014. Paratypes: 1 female (cl 14.9 mm, pcl 12.6 mm, cw 10.0 mm, pcw 9.2 mm) (MNHN-IU-2014-18677b), same data as holotype; 1 ovigerous female (cl 17.7 mm, pcl 15.4 mm, cw 12.9 mm, pcw 12.2 mm) (ZRC 2022.73 ex MNHN-IU-2014-10019), stn DW 4415, New Ireland, 02°31’S 150°38’E, 212–214 m, coll. N.O. Alis, KAVIENG 2014 expedition, 27 August 2014. All specimens from Papua New Guinea.
Diagnosis. Small-sized species (ovigerous female less than 17 mm long); regions well defined; base of epigastric region with 2 short spines, meso- and metagastric regions with 1 median spine each, protogastric spines with 1 short oblique spine, cardiac region with 2 laterally positioned short spines, intestinal region with 2 short spines, branchial region with 1 prominent anterior spine and 1 short posterior spine, lateral branchial margin with 7–9 larger spines and many smaller ones, hepatic region with 2 strong spines; rest of carapace covered with short spinules and sharp granules (Figs. 14, 15A–C, 16A, B); pseudorostral spines clearly diverging, forming V-shape, each spine relatively short, with 4 lateral accessory spines; ventral surface with 2 spines; distal border of antennular fossa with strong distal anteriorly directed spine; supraorbital eave relatively low, narrow, preorbital tooth long, margin of eave with 5 spines, proximal one small, no obvious large antorbital spine; intercalated spine distinct, smaller than prominent postorbital spine (Fig. 15A–D); interantennular spine bifid distally (Fig. 15D); basal antennal article long with 2 distal spines, one larger, outer margin with 3 spines, inner margin with 1 short spine, first article with prominent lateral spine (Fig. 16C, D). Third maxilliped pediform: ischium with 2 longitudinal rows of sharp granules on outer surface, lateral row with 8 tubercles, mesial row with 5 tubercles; merus subtriangular, longer than broad, with 4 sharp tubercles on outer surface, exopod with row of 9 tubercles or granules (Fig. 16E, F). Cheliped palm not inflated; propodal margin below articulation of dactylus and pollex with low subtruncate granulated process; cutting edge fingers with evenly sized teeth, those on proximal part of dactylus slightly larger (Fig. 17B). Distal margin of pleonal somite 6 deeply concave (Fig. 16E). G1 relatively slender, slightly curved along basal two-thirds, distal part bent outwards, forming ca. 60° angle, distal part elongate, with small subdistal process (Figs. 17C–E, 18A–D). G2 about a third length of G1, tip spatuliform (Figs. 17F, 18E).
Female. The females agree well with the male in all non-sexual aspects. The female pleon has somites 1–5 free (each with a median tubercle), with somites 1–3 relatively narrow and somites 4–6 increasingly wider; somite 6 is functionally fused to the telson although the suture is still visible; the structure appearing almost round in ventral view, prominently dome-shape with the telson semicircular (Fig. 17G). The vulva is large and open laterally on a raised part of sternite 6 (Fig. 17H).
Colour. The carapace is pale yellow to orange with the chelipeds and ambulatory legs orangish-red with patches of white (Fig. 1D).
Etymology. The name is derived from the French word “aie” for an exclamation of pain, alluding to the prickly features of the species. The name is used as a Latin noun in apposition.
Remarks. The present new species is closest to P. japonica, known from only a few specimens, all from Japan (Yokoya 1933: 140, text-fig. 50; Takeda & Miyake 1969: 494, pl. 18, fig. A, text-fig. 9c, d; Sakai 1976: 174; Sakai 1986: 238; 1940: 55; Richer de Forges et al. 2013: 17, figs. 1–3, 6A–E). Parapleisticantha aie n. sp., however, differs from P. japonica in having the carapace proportionately longer (Figs. 14, 15A, B; cf. Richer de Forges et al. 2013: figs. 1A, B, 3A, B); the basal antennal article is distinctly more elongate (Fig. 16C, D; cf. Richer de Forges et al. 2013: fig. 1C); the third maxilliped ischium is proportionately longer (Fig. 16F; cf. Richer de Forges et al. 2013: fig. 2C); and most significantly, the G1 has the distal part less distinctly curved with the tapering tip more elongate and there is a small subdistal fold (Fig. 17C–E, 18C, D) (versus G1 distal part curving at almost right angles with the tip shorter and there is no trace of a subdistal flap in P. japonica; cf. Richer de Forges et al. 2013: fig. 6A–D).
The holotype male is not fully mature as its chelae are still relatively slender (Fig. 17B); in adult males of Parapleisticantha, the chelae are inflated and stout (Richer de Forges et al. 2013: figs. 2E, 5E).
description: Published as part of Ng, Peter K. L., Forges, Bertrand Richer De & Lee, Bee Yan, 2023, New and rare deep-sea majoid crabs (Crustacea: Brachyura) from Papua New Guinea, pp. 1-44 in Zootaxa 5318 (1) on pages 19-20, DOI: 10.11646/zootaxa.5318.1.1, http://zenodo.org/record/8158079