Parapontophilus geminus, 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 : 302-305

Parapontophilus geminus n. sp.

( Figs 17 ; 20F )

Pontophilus gracilis abyssi – Chace 1984: 47 (key), 49, figs 16, 17, 23c.

TYPE MATERIAL. — Holotype: Japan. RV Tansei-maru, KT05-30 cruise, stn HB, Hyuga Basin, 32°22.58’N, 132°30.54’E, 1644-1657 m, 22.XI.2005, beam trawl, coll. H. Karasawa, ♀ 11.1 mm ( CBM-ZC 8764). Paratypes: Japan. Same data as holotype, 1 ♂ 9.8 mm ( CBM-ZC 8765). Taiwan. TAIWAN2002,stnCP184, 21°51.5’N, 119°27.63’E, 2542- 2516 m, 26.VIII.2002, 1 ♀ 11.1 mm ( NTOU). — Stn CP 185, 22°00.54’N, 119°27.94 E, 2334-2543 m, 26.VIII.2002, 3 ♀♀ 12.0- 13.3 mm ( NTOU). — Stn CP 189, 21°39.91’N, 118°20.94’E,1649- 1629 m, 27.VIII.2002, 2 ♀♀ 12.4, 13.0 mm ( NTOU). TAIWAN 2003, stn CP 285, 24°16.09’N, 122°11.52’E, 2268-2426 m, 16. VI.2003, 2 ♂♂ 9.3 mm, not measured (damaged), 1 ♀ 12.6 mm ( NTOU). TAIWAN 2005, stn CD 325, 20°44.79’N, 117°59.65’E, 1982- 1794 m, 20.VIII.2005, 1 ♂ 9.4 mm, 1 ♀ 10.0 mm ( NTOU). — Stn CP 363, 1 ♀ 12.3 mm ( NTOU). OTHER MATERIAL EXAMINED. — Taiwan. TAIWAN 2003, stn CP 284, 24°16.34’N, 122°11.67’E, 16. VI.2003, 1 ♂ 12.6 mm (badly damaged) ( NTOU).

Philippines. ESTASE 2, stn CP 2, 14°05.40’N, 120°02.46’E, 2050 m, 14.XI.1984, 1 ♀ 11.0 mm (MNHN-Na 16201).

Indonesia. Challenger, stn 184, Torres Strait, 12°08’S, 145°10’E, 2520 m, 29.VIII.1874, 1♂ 12.2 mm, paratype of Pontophilus gracilis Bate, 1888 ( BMNH 1888.22).

CORINDON 2 (Makassar Strait), stn CP 220, 00°13.6’N, 118°12.3’E, 2340 m, 2.XI.1980, 2 ♀♀ not measured (MNHN-Na 5320).

ETYMOLOGY. — From the Latin geminus , meaning twin, in reference to the close similarity of this new species to P. difficilis n. sp.

DISTRIBUTION. — Japan, Taiwan, Philippines and Makassar Strait in Indonesia ( Fig. 35 ), 1644-2520 m.

DESCRIPTION

Rostrum ( Fig. 17 A-D) moderately broad triangular in dorsal view, 0.16 of carapace length, directed forward, not reaching distal margins of corneas; dorsal surface faintly concave in proximal half; lateral margins armed with 2 pairs of small teeth, anterior pair arising proximal to midlength. Carapace ( Fig. 17A, C, D ) 1.60 times longer than wide; anterior epigastric tooth smaller than posterior epigastric tooth; posterior epigastric and cardiac teeth moderately small; postorbital tooth minute; postorbital and epibranchial ridges low, but discernible; branchiostegal tooth not reaching dorsodistal margin of antennal basicerite.

Third pleonal somite ( Fig. 17E ) with moderately convex tergum and moderately produced posterodorsal margin. Fifth somite ( Fig. 17E, F ) rounded on dorsal surface. Sixth somite ( Figs 17 ; 18E, F ) 3.70-4.00 times longer than wide, 2.50-2.60 times as long as deep; dorsal surface rounded.

Eye ( Fig. 17A ) rounded; cornea lightly pigmented in preservative (colour opaque with tinge of brown posterolaterally on dorsal surface); corneal surface distinctly faceted with comparatively small lenses ( Fig. 20F ); maximal diameter of cornea 0.14-0.15 of carapace length; boundary between cornea and eye-stalk clearly delineated; eye-stalk not constricted; papillalike projection on mesial face small. Antennular peduncle ( Fig. 17A ) falling short of midlength of antennal scale. Antennal scale ( Fig. 17A ) 0.65 of carapace length, 3.90 times longer than wide; lateral margin slightly concave, distolateral tooth slightly falling short of distal margin of lamella.

Palm of first pereopod ( Fig. 17G ) rather elongate, 4.00-4.50 times longer than wide; cutting edge strongly oblique; pollex moderately small, width of palm including tip of pollex 1.40 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. Fourth pereopod ( Fig. 17H ) relatively slender; dactylus subspatulate, 0.62 of propodal length; carpus 0.75 of propodal length. Fifth pereopod similar to fourth, slightly falling short of distal margin of antennal scale.

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

Coloration in life

Unknown.

In preservative, carapace, cephalic and thoracic appendages generally light reddish-brown; eyes opaque; abdomen entirely white.

Size

Males CL 9.3-11.0mm; females CL 10.0- 13.3mm.

REMARKS

Parapontophilus geminus n. sp. is morphologically very similar to P. difficilis n. sp. Particularly, the structure of the cornea is similar between the two species. Nevertheless, the cornea is distinctly smaller in P. geminus n. sp. than in P. difficilis n. sp. (the maximal diameter is 0.14-0.15 of the carapace length versus 0.18-0.20). Th e shape of the rostrum is also different between the two. In P. geminus n. sp., the rostrum is more strongly narrowed distally with distinctly concave lateral margins ( Fig. 17B ). In contrast, the rostrum of P. difficilis n. sp. tapers gradually toward the tip with nearly straight lateral margins ( Fig. 14D ).

As discussed before, specimens from the Philippines, referred to Pontophilus gracilis abyssi by Chace (1984), most probably represent P. geminus n. sp.

A review of Parapontophilus ( Crustacea, Decapoda )

Figures

FIG. 17. –– Parapontophilus geminus n. sp., ♀ 11.2 mm,holotype,Hyuga-nada Sea,Japan (RV Tansei-maru, KT05-30,stn HB) (CBM-ZC 8764): A, carapace and cephalic appendages,dorsal view;B, rostrum,dorsal view;C, carapace,lateral view;D, anterior part of carapace, cornea,and basal part of antennae,lateral view; E, third to sixth pleonal somites,lateral view;F, fourth to sixth pleonal somites,dorsal view; G, subchela of left first pereopod, ventral view; H, right fourth pereopod, lateral view. Scale bars: A, C-H, 2 mm; B, 1 mm.

FIG. 20. — Eyes of selected species of the Parapontophilus gracilis group: A, P. gracilis (Smith, 1882), ♀ 8.6 mm, Senegal, west Africa (MNHN-Na 5258); B, P. abyssi (Smith, 1884), ♀ 15.2 mm, northeastern Atlantic (INCAL, stn CP 15) (MNHN-Na 4318); C, P. junceus (Bate, 1888), ♀ 7.4 mm, Austral Islands, French Polynesia (BENTHAUS, stn CP 1967) (MNHN-Na 16156); D, P. occidentalis (Faxon, 1893),syntype ♀ 18.5 mm,Gulf of Panama, eastern Pacific (Albatross, stn 3382) (MZC 4584); E, P.difficilis n. sp., holotype ♀ 13.3 mm, Vanuatu (MUSORSTOM 8, stn CP 1129) (MNHN-Na 16174); F, P. geminus n. sp., holotype ♀ 11.1 mm, Hyuga-nada, Japan (Tanseimaru, KT05-30, stn HB) (CBM-ZC 8764).

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) (✚).

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. 14. — Parapontophilus difficilis n. sp.: 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, second to sixth pleonal somites,lateral view; F, fifth and sixth pleonal somites,dorsal view;G, subchela of left first pereopod,ventral view;H, left fourth pereopod, lateral view; A-D, F-H, ♀ 13.3 mm, holotype, Vanuatu (MUSORSTOM 8, stn CP 1129) (MNHN-Na 16174); E, ♀ 13.8 mm, paratype, Solomon Islands (SALOMON 2, stn CP 2230) (MNHN-Na 16196). Scale bars: A, B, F, 5 mm; C-E, G, H, 2 mm.