Parapontophilus longirostris, Komai, 2008

Komai, Tomoyuki, 2008, A world-wide review of species of the deepwater crangonid genus Parapontophilus Christoffersen, 1988 (Crustacea, Decapoda, Caridea), with descriptions of ten new species, Zoosystema 30 (2), pp. 261-332 : 305-309

Parapontophilus longirostris n. sp. ( Figs 18 ; 19 ; 21A )

Pontophilus gracilis abyssi – Allen & Butler 1994: 440. Not Pontophilus gracilis abyssi Smith, 1884 .

TYPE MATERIAL. — Holotype: Austral Islands . BENTHAUS, stn CP 1965, Tubuai Island, 23°21.3’S, 149°33.9’W, 19.XI.2002, 1 ♀ 8.5 mm (MNHN-Na 16210).

Paratypes: Austral Islands. BENTHAUS, same data as holotype, 4 ♂♂ 7.1-8.0 mm, 2 ♀♀ 7.6-8.6 mm (MNHN-Na 16211). — Stn CP 1892, E of Rapa Island, 27°38.8’S, 144°15.6’W, 742-1000 m, 7.XI.2002, 1 ♂ 5.8 mm, 3 ♀♀ 6.3-6.5 mm (MNHN-Na 16212). — Stn CP 1909, E of Rapa Island, 27°38.6’S, 144°15.6’W, 783-1000 m, 13.XI.2002, 1 ♂ 5.8 mm, 1 ♀ 6.1 mm (MNHN-Na 16213).

OTHER MATERIAL EXAMINED. — Western Indian Ocean. Comoros Islands ( Mayotte), BENTHEDI, stn CH 31, 12°37.4’S, 45°25.2’E, 1800 m, 25.III.1977, 1 ♂ 7.3 mm (MNHN-Na 16214).

Réunion Island, Marion Dufresne, cruise MD 32, stn DS 139, 1600- 1575 m, 3.IX.1982, 4 ♂♂ 6.7-8.0 mm, 2 ♀♀ 6.0, 7.2 mm (MNHN-Na 16215). — Stn CP 140, 20°41.2’S, 55°38.2’E, 1612-1680 m, 3.IX.1982, 1 ♀ 8.9 mm (MNHN-Na 16216).

Japan. TV Toyoshio-maru, 1996-5 cruise, stn 5, off Cape Toi, Miyazaki Prefecture, 31°17.74’N, 131°53.2’E, 1160- 1114 m, mud bottom, 1. VI.1996, ORI net accidentally on bottom, coll. T. Komai, 1 ♀ 8.9 mm ( CBM-ZC 8184).

Taiwan. TAIWAN 2005, stn CP 281, 24°24.08’N, 122°14.06’E, 1173-1248 m, 15. VI.2005, 1 ♀ 7.6 mm ( NTOU).

New Caledonia. BIOCAL, stn CP 61, 24°11’S, 167°32’E, 1070 m, 2.IX.1985, 1 ♀ 7.3 mm (MNHN- Na 16217).

Vanuatu. MUSORSTOM 8, stn CP 956, 20°33.41’S, 169°35.95’E, 1175-1210 m, 20.IX.1994, 1 ♀ (crashed) (MNHN-Na 16218).

Marquesas Islands. MUSORSTOM 9, stn CP 1278, Eiao Island, 07°52’S, 140°39’W, 1000 m, 5.IX.1997, 1 ♂ 7.6 mm, 4 ♀♀ (all crashed) (MNHN-Na 16219). Mid-Pacific mountains. RV Hakuho-maru, KH93-1 cruise, stn 7, Sio Guyot, 18°16.05’N, 171°20.99’E, 1300-1312 m, 31.I.1993, beam trawl with 4 m span opening, coll. I. Takeuchi, 3♀♀ 6.5-7.7 mm ( CBM-ZC 8761).

ETYMOLOGY. — Combination of the Latin words longus (long) and rostellum (beaked), alluding to the comparatively long rostrum of this new species.

DISTRIBUTION. — Comoros and Réunion islands in the western Indian Ocean, Japan, Taiwan, New Caledonia, Vanuatu, French Polynesia and Mid-Pacific mountains in the Pacific Ocean ( Fig. 35 ), 742-1800 m.

DESCRIPTION

Rostrum ( Fig. 19 A-D) narrow triangular in dorsal view,0.20-0.25 of carapace length, usually somewhat directed upward, overreaching distal margins of corneas; dorsal surface flat or faintly concave in proximal half; lateral margins armed with 1 or 2 small teeth proximal to midlength. Carapace ( Figs 18 ; 19 A-D) 1.70-1.80 times longer than wide, with 1 or 2 tiny anterior epigastric teeth; posterior epigastric and cardiac teeth moderately small; postorbital tooth minute, occasionally absent; epibranchial ridge low, sometimes obsolete; branchiostegal tooth usually reaching dorsodistal margin of antennal basicerite.

Third pleonal somite ( Fig. 18 ) with moderately convex tergum and moderately produced posterodorsal margin. Fifth somite ( Fig. 19E ) rounded on dorsal surface. Sixth somite ( Figs 18 ; 19E, F ) 4.00-4.10 times longer than wide, 3.00-3.30 times as long as greatest depth; dorsal surface rounded.

Eye ( Fig. 19A, D, G ) subpyriform; cornea lightly pigmented in preservative (colour generally yellow or light brown, usually with darker brown patch on dorsal surface); corneal surface distinctly faceted with comparatively large lenses ( Fig. 21A ); maximal diameter of cornea 0.12-0.13 of carapace length; boundary between cornea and eye-stalk clearly delineated; eye-stalk noticeably constricted; papilla-like projection on mesial face relatively large ( Fig. 19G ). Antennular peduncle ( Fig. 19A ) falling short of midlength of antennal scale. Antennal scale ( Fig. 19A ) 0.60-0.70 of carapace length, 3.90-4.10 times longer than wide; lateral margin slightly concave, distolateral tooth reaching distal margin of lamella.

Palm of first pereopod ( Fig. 19H ) elongate, 4.00-4.80 longer than wide; cutting edge strongly oblique; pollex moderately small, width of palm including tip of pollex 1.40-1.50 of width proximal to base of pollex; merus with relatively weak dorsodistal tooth. Second pereopod short, reaching or falling short of midlength of merus of first pereopod ( Fig. 18 ). Fourth pereopod ( Fig. 19I ) overreaching distal margin of antennal scale by half to full length of dactylus; dactylus subspatulate, 0.50-0.60 of propodal length; carpus 0.80-0.90 of propodal length. Fifth pereopod similar to fourth, slightly falling short of distal margin of antennal scale.

Appendix masculina of male second pleopod 0.60-0.70 length of appendix interna.

Coloration in life

Unknown.

Size

Males CL 5.8-8.0 mm; females CL 6.0- 8.9 mm.

REMARKS

Specimens from various localities are generally similar, and I could not find any morphological differences associated with geographical pattern.The rostrum is usually armed with two pairs of lateral teeth, but one or both of the anterior pairs occasionally missing like in other congeneric species.

This new species can be easily distinguished from the other species of the Parapontophilus gracilis group by the rostrum clearly overreaching the anterior margins of the corneas, the elongate sixth pleonal somite (3.00-3.30 times longer than deep), the comparatively small corneas (the maximum diameter of the cornea is 0.12-0.13 of the carapace length) with a distinctly faceted corneal surface, the noticeably constricted eye-stalk, and the elongate palm of the first pereopod (4.00-4.80 times as long as wide).

Allen & Butler (1994) recorded Pontophilus gracilis abyssi from the Mid-Pacific mountains, although they did not provide information on morphology of their specimens. The present material contains three specimens from SIO Guyot, Mid-Pacific mountains. Therefore I assume that Allen & Butler’s (1994) specimens may actually represent the present new species. The occurrence of the true P. abyssi in the Pacific Ocean has not been confirmed during this study.

Figures

FIG. 18. — Parapontophilus longirostris n. sp., habitus, lateral view, ♂ 7.8 mm, non-type, off Réunion Island, western Indian Ocean (MD 32, stn DS 139) (MNHN-Na 16215). Scale bar: 5 mm.

FIG. 19. — Parapontophilus longirostris n. sp., ♀ 8.5 mm, holotype, Tubuai Island, Austral Islands, French Polynesia (BENTHAUS, stn CP 1965) (MNHN-Na 16210):A, carapace and cephalic appendages,dorsal view;B, carapace,lateral view;C, anterior part of carapace, cornea and basal part of antennae, lateral view; D, anterior part of carapace and eyes, dorsal view; E, fifth and sixth pleonal somites, dorsal view;F, sixth pleonal somite, lateral view; G, eye,ventromesial view; H, subchela of left first pereopod, ventral view; I, dactylus, propodus and carpus of left fourth pereopod, lateral view. Scale bars: A, B, E, F, 2 mm; C, D, G-I, 1 mm.

FIG. 21. –– Eyes of selected species of Parapontophilus: A, P. longirostris n. sp., holotype ♀ 8.5 mm, Tubuai Island, Austral Islands, French Polynesia (BENTHAUS,stn CP 1965) (MNHN-Na 16210);B, P.demani (Chace,1984),♀ 4.9 mm,off Shionomisaki,Kii Peninsula, Japan (CBM-ZC 8648).

FIG. 35.— Geographic distribution of Parapontophilus abyssi (Smith,1884) (■), P.cornutus n. sp.(❖), P.cyrton n. sp.(✽), P.difficilis n. sp. (▼), P. geminus n. sp. (✖), P. junceus (Bate, 1888) (●), P. longirostris n. sp. (▲), P. occidentalis (◆) and P. profundus (Bate, 1888) (✚).