Parilia pattersoni Ng & Devi & Kumar 2018, new species
Creators: name: Ng, Peter K. L.
name: Devi, Suvarna
name: Kumar, Appukuttannair Biju
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Leucosiidae
Parilia
Parilia pattersoni

description: Parilia pattersoni, new species
(Figs. 1D, 2C, 3D, 4G, H, 5 G–I, 6D, 7G, H, 8N–S, 9E, F)
Parilia alcocki – Doflein, 1904: 44, pl. 14 figs. 8, 9 (not Wood-Mason, in Wood-Mason & Alcock, 1891).
Parilia major – Vidhya et al., 2017: 2334 (not Sakai, 1961).
Material examined. Holotype: male (53.0 × 52.6 mm) (DABFUK), Tuticorin fishing port, Tamil Nadu, southeastern India, coll. A.B. Kumar et al., March 2017. Paratypes: 2 males (47.7 × 48.6 mm, 72.5 × 69.8 mm), same data as holotype; 3 males (64.4 × 63.5 mm, 54.1 × 53.8 mm, 50.0 × 49.4 mm), 2 females (58.2 × 55.8 mm, 52.6 × 54.0 mm, 51.0× 51.7 mm, 46.0 × 45.7 mm) (DABFUK), same location as holotype, coll. R. Ravinesh, February 2017.
Diagnosis. Carapace globose (Figs. 1D, 2C, 3D); dorsal surface covered with numerous small granules (Fig. 3D); branchial regions not distinctly swollen laterally and dorsally, lateral margin of carapace covered with small granules (Fig. 3D); dome-shape in frontal view (Fig. 4G); frontal region protruding anteriorly with buccal cavity and third maxillipeds not visible in dorsal view, frontal lobes distinctly triangular (Fig. 3D); outer surface of third maxillipeds covered with numerous small granules (Figs. 4G, H, 5 G–I); exopod of third maxilliped in adult broad but not foliaceous (Fig. 5 G–I); surfaces of ambulatory legs and chelipeds covered with numerous distinct small sharp tubercles and granules (Figs. 1D, 2C, 6D); G1 very elongate, distal part flared, subdistal lateral projection dorso-ventrally flattened (Fig. 8 N–R); female sternopleonal cavity without projection between vulvae (Fig. 9F).
Description of adult male. Carapace almost globose, slightly longer than broad; surface covered with numerous small but clearly visible granules (more prominent in large specimens); hepatic region adjacent to anterolateral margin not prominently swollen, just visible in dorsal view; gastric and branchial regions convex but not prominently swollen; dorsal surface evenly convex; oblique cervical groove very shallow, not clearly visible, with a shallow pit marking junction with gastric region; cardiac region swollen, with posteriorly directed tooth, separated from gastric and branchial regions by distinct sub-longitudinal grooves; gastro-cardiac groove distinct, separating cardiac and intestinal regions from swollen branchial regions, small rugose area present at junction of groove between anterior part of cardiac region and branchial region; low but visible median longitudinal ridge present from gastric to cardiac region; intestinal region low, pushed behind by swollen cardiac region, not well defined; carapace appears dome-like from frontal view (Figs. 1D, 3D, 4G). Antennae with short flagellum, not extending beyond orbit (Fig. 4G). Antennules folding obliquely (Fig. 4G). Orbit small, rounded; eye with short peduncle; supraorbital margin with 2 prominent fissures, inner one longer; suborbital margin with distinct low tooth on inner margin (Fig. 4G, H). Epistome wide, median part not projecting anteriorly, with deep median fissure; lateral part of epistome not visible from dorsal view; endostomial ridge strong, longitudinal (Fig. 4G, H).
Frontal margin distinct, produced anteriorly, bilobed, with broadly triangular concavity separating broadly triangular lobes; most of ptergygostomial regions and epistome not visible in dorsal view (Figs. 1D, 3D). Anterior half of anterolateral margin relatively low, starting as low ridge of granules from supraorbital margin, becoming more prominently cristate and granular towards posterior half which has 2 or 3 low teeth, the last one most prominent (Figs. 1D, 3D). Pterygostomial region wide, not visible in dorsal view; anterior tooth adjacent to buccal cavity bilobed, separated from margin by cleft; posterior tooth before anterolateral margin low but distinct (Fig. 4G). Posterolateral margin strongly convex, entire except for tooth just before posterior carapace margin (Figs. 1D, 3D). Posterior carapace margin with 2 prominent lateral sharp teeth (Figs. 1D, 3D).
Buccal cavity wide, about half width of carapace; not protruding anteriorly; third maxillipeds sloping in lateral view when closed (Fig. 4G, H). Third maxillipeds completely covering buccal space when closed; surfaces with numerous small but distinct granules; palp (carpus, propodus and dactylus) concealed behind merus when retracted, longer than merus; merus shorter than ischium, with triangular distal margin, lined with setae; ischium with very shallow submedian oblique sulcus; exopod very broad but not foliaceous, wider than ischium with outer margin strongly convex; main part of coxa deeply inserted into cephalothorax, external surface with wide, almost semicircular plate extending from base, bracketing base of wide exopod (Figs. 4H, 5 G–I). Surfaces of sub-orbital, pterygostomial, sub-hepatic and sub-branchial regions covered with distinct small granules; anterior margin of pterygostomial region subcristate; sub-branchial and ptergygostomial regions separated by distinct oblique groove (Fig. 4G, H).
Chelipeds very long, slender, surfaces of merus, carpus and palm covered with numerous small distinct sharp granules; merus long, cylindrical; carpus short; palm subcylindrical, with distal part proportionately broader, elongated, at least twice length of carapace in largest specimens; palm more than 2.5 times length of slender fingers; dactylus gently curved; basal part of propodal finger slightly arched, forming just visible gape with dactylus when closed; cutting edges of fingers (occluding surfaces) with small teeth (Figs. 1D, 6D).
Ambulatory legs long, slender; first leg longest, last leg shortest; surfaces of merus, carpus and propodus covered with small sharp granules; merus and propodus subcylindrical, not armed with spines or setae; dactylus gently curved, dorsoventrally flattened, each dorsal margin with dense row of setae, tip rounded (Fig. 1D).
Thoracic sternum with surfaces almost smooth; sternites 1–4 completely fused, forming one plate without trace of sutures (Fig. 7G, H); sutures between sternites 4–8 medially interrupted; pleonal locking mechanism consisting of projecting edges of sternites 5–7, no trace of peg or tubercle on sternite 5. Sternopleonal cavity deep, reaching to just before groove separating thoracic sternites 2 and 3 (Fig. 7G). Small part of thoracic 8 exposed when pleon closed, visible as small plate at anterolateral edge of somite 3 (Fig. 7H). Penis tubular, exiting on condyle of coxa of fourth ambulatory leg.
Pleon elongate, triangular, surface smooth; somites 1 and 2 free; somites 3–5 completely fused, with only short transverse median groove visible between somites 3 and 4, lateral margin sinuous; somite 3 widest, lateral margins reaching coxae of fourth ambulatory legs; somite 6 long, trapezoidal; telson acutely triangular (Fig. 7G, H). G1 elongate, basal part broadest, median and distal parts slender, tubular, gently curved from ventral view; distal part bifurcated, longer projection directed inwards towards median of thoracic sternum, distal part flared to form prominent dorso-ventrally flattened flange, margin of flange serrulate, shorter projection in line with rest of G1, distal part flared with denticulate margin on flange (Fig. 8 N–R). G2 short, distal segment as long as basal segment, with curved flagelliform tip (Fig. 8S).
Female. Chelipeds relatively shorter (Fig. 2C). Pleon strongly convex, dome-like; somite 1 free, somites 2–6 functionally fused with sutures still visible, telson mobile; telson triangular with distinctly concave lateral margins; surface of somites smooth (Fig. 9E). Sternopleonal cavity large, deep, with prominent rim, completely covered by pleon; sutures separating thoracic sternites 4–8 all medially interrupted, median part of cavity smooth; vulvae on anterior edge of sternite 6, pushing into sternite 5, opening crescent-shaped, with narrow operculum, inner margin slightly raised (Fig. 9F). Eggs small, numerous, brown when fresh.
Colour. Freshly caught, the adult carapace and chelipeds are pale whitish-orange with the ambulatory legs white.
Etymology. The species is named after Edward J. K. Patterson, noted marine biologist and director of the Suganthi Devadason Marine Research Institute in Tuticorin, Tamil Nadu, India, who kindly hosted the authors during their work there.
Remarks. Parilia pattersoni, new species, is morphologically closest to P. major but can easily be distinguished by having the surfaces of the ambulatory meri and chelipeds covered with distinct small granules and sharp tubercles (Figs. 1D, 2C, 6D) (vs. completely smooth in P. major; Figs. 1B, 2B, 6B); the dorsal carapace surface and margins are covered with small sharp granules (Figs. 3D, 4G) (vs. smooth to almost smooth with very small flattened granules in P. major; Figs. 3B, 4C); the surface of the pterygostomial and sub-branchial regions as well as the outer surface of third maxillipeds are covered with distinct small granules (Figs. 4G, H, 5 G–I) (vs. smooth or with very small, almost flattened granules in P. major; Figs. 4C, D, 5D, E); the outer surface of the chela in both sexes are distinctly covered with sharp granules (Fig. 6D) (vs. outer surface of chela completely smooth in P. major; Fig. 6B); the cardiac spine is proportionately shorter even in smaller specimens (Figs. 1D, 2C, 3D) (vs. spine always proportionately longer in P. major; Figs. 1B, 2B, 3B); and the lateral distal process of the G1 is relatively shorter (Fig. 8P, Q) (vs. relatively longer in P. major; Fig. 8F, G).
Doflein (1904: 44, pl. 14 figs. 8, 9) recorded and figured a male specimen (without chelipeds) of “ Parilia alcocki ” from off the island of Nias in eastern Sumatra (incorrectly recorded as a female) and there have been doubts about its precise identity. Sakai (1961: 137) commented that the “ P. alcocki Doflein (nec Wood-Mason) may be a different species; the carapace of Doflein’s species seems to be circular in outline just as in the new species [P. major], but the merus and carpus of the pereiopods are spinulated along the posterior border.” Tirmizi & Serène (1971: 31) agreed but deferred acting on it; neither did Prema et al. (2018). It is clear from the figure in Doflein (1904: pl. 14 figs. 8, 9) that the carapace shape is quite different from that of P. alcocki s. str., being globose rather than transversely subovate. Doflein’s (1904) figures also show the carapace margins as lined with fine granules and the surfaces of the ambulatory meri covered with spinules; characters associated with P. pattersoni, new species, as defined here. Vidhya et al. (2017) listed Parilia major from the southeast coast of India but their record is probably also P. pattersoni as well.
Distribution. Known thus far only from eastern India (present study) and western Sumatra in Indonesia (Doflein, 1904, as “ P. alcocki ”). Doflein’s (1904) specimen was from a depth of 141 m, and the present material was probably obtained from depths between 100– 300 m.
description: Published as part of Ng, Peter K. L., Devi, Suvarna & Kumar, Appukuttannair Biju, 2018, The genus Parilia Wood-Mason, in Wood-Mason & Alcock, 1891, with description of a new species and establishment of a new genus for P. tuberculata Sakai, 1961 (Crustacea, Brachyura, Leucosiidae), pp. 300-319 in Raffles Bulletin of Zoology 66 on pages 305-309, DOI: 10.5281/zenodo.4503189