Parilia pattersoni, Ng & Devi & Kumar, 2018

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), Raffles Bulletin of Zoology 66, pp. 300-319 : 305-309

publication ID	https://doi.org/ 10.5281/zenodo.4503189
publication LSID	lsid:zoobank.org:pub:CBB28174-9B04-4A65-8C7C-5EB4B3608D98
DOI	https://doi.org/10.5281/zenodo.4778998
persistent identifier	https://treatment.plazi.org/id/D3A48F6D-1BA3-4304-B68C-6CDC28B0837F
taxon LSID	lsid:zoobank.org:act:D3A48F6D-1BA3-4304-B68C-6CDC28B0837F
treatment provided by	Carolina
scientific name	Parilia pattersoni
status	sp. nov.

Treatment

Parilia pattersoni View in CoL , new species

( Figs. 1D View Fig , 2C View Fig , 3D View Fig , 4G, H View Fig , 5 View Fig 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 View in CoL – 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 View Fig , 2C View Fig , 3D View Fig ); dorsal surface covered with numerous small granules ( Fig. 3D View Fig ); branchial regions not distinctly swollen laterally and dorsally, lateral margin of carapace covered with small granules ( Fig. 3D View Fig ); dome-shape in frontal view ( Fig. 4G View Fig ); frontal region protruding anteriorly with buccal cavity and third maxillipeds not visible in dorsal view, frontal lobes distinctly triangular ( Fig. 3D View Fig ); outer surface of third maxillipeds covered with numerous small granules ( Figs. 4G, H View Fig , 5 View Fig G–I); exopod of third maxilliped in adult broad but not foliaceous ( Fig. 5 View Fig G–I); surfaces of ambulatory legs and chelipeds covered with numerous distinct small sharp tubercles and granules ( Figs. 1D View Fig , 2C View Fig , 6D View Fig ); G1 very elongate, distal part flared, subdistal lateral projection dorso-ventrally flattened ( Fig. 8 View Fig N–R); female sternopleonal cavity without projection between vulvae ( Fig. 9F View Fig ).

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 View Fig , 3D View Fig , 4G View Fig ). Antennae with short flagellum, not extending beyond orbit ( Fig. 4G View Fig ). Antennules folding obliquely ( Fig. 4G View Fig ). 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 View Fig ). 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 View Fig ).

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 View Fig , 3D View Fig ). 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 View Fig , 3D View Fig ). 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 View Fig ). Posterolateral margin strongly convex, entire except for tooth just before posterior carapace margin ( Figs. 1D View Fig , 3D View Fig ). Posterior carapace margin with 2 prominent lateral sharp teeth ( Figs. 1D View Fig , 3D View Fig ).

Buccal cavity wide, about half width of carapace; not protruding anteriorly; third maxillipeds sloping in lateral view when closed ( Fig. 4G, H View Fig ). 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 View Fig , 5 View Fig 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 View Fig ).

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 View Fig , 6D View Fig ).

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 View Fig ).

Thoracic sternum with surfaces almost smooth; sternites 1–4 completely fused, forming one plate without trace of sutures ( Fig. 7G, H View Fig ); 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 View Fig ). Small part of thoracic 8 exposed when pleon closed, visible as small plate at anterolateral edge of somite 3 ( Fig. 7H View Fig ). 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 View Fig ). 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 View Fig N–R). G2 short, distal segment as long as basal segment, with curved flagelliform tip ( Fig. 8S View Fig ).

Female. Chelipeds relatively shorter ( Fig. 2C View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig , 2C View Fig , 6D View Fig ) (vs. completely smooth in P. major ; Figs. 1B View Fig , 2B View Fig , 6B View Fig ); the dorsal carapace surface and margins are covered with small sharp granules ( Figs. 3D View Fig , 4G View Fig ) (vs. smooth to almost smooth with very small flattened granules in P. major ; Figs. 3B View Fig , 4C View Fig ); 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 View Fig , 5 View Fig G–I) (vs. smooth or with very small, almost flattened granules in P. major ; Figs. 4C, D View Fig , 5D, E View Fig ); the outer surface of the chela in both sexes are distinctly covered with sharp granules ( Fig. 6D View Fig ) (vs. outer surface of chela completely smooth in P. major ; Fig. 6B View Fig ); the cardiac spine is proportionately shorter even in smaller specimens ( Figs. 1D View Fig , 2C View Fig , 3D View Fig ) (vs. spine always proportionately longer in P. major ; Figs. 1B View Fig , 2B View Fig , 3B View Fig ); and the lateral distal process of the G1 is relatively shorter ( Fig. 8P, Q View Fig ) (vs. relatively longer in P. major ; Fig. 8F, G View Fig ).

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.