Parapontophilus difficilis, 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 : 297-302

Parapontophilus difficilis n. sp.

( Figs 6C ; 14-16 ; 20E )

Pontophilus occidentalis var. indica de Man, 1918: 161 (part); 1920: 264 (part), pl. 20, fig. 63, 63a, pl. 21, fig. 63b-v.

Pontophilus gracilis junceus – Chace 1984: 49 (part), figs 16, 17.

TYPE MATERIAL. — Holotype: Vanuatu. MUSORSTOM 8, stn CP 1129, 16°00.73’S, 166°39.94’E, 1014-1050 m, 10.X.1994, ♀ 13.3 mm (MNHN-Na 16174).

Paratypes: Vanuatu. MUSORSTOM 8, stn CP 990, 18°51.63’S, 168°50.98’E, 980-990 m, 24.IX.1994, 1 ♀ 12.0 mm (MNHN-Na 16175). — Stn CP 991, 18°51.26’S, 168°52.19’E, 936- 910 m, 24.IX.1994, 8♀♀ 9.1-12.6 mm (MNHN-Na 16176). — Stn CP 1008, 18°53.29’S, 168°52.65’E, 919-1000 m, 25.IX.1994, 2 ♂♂ 8.4, 8.4 mm (MNHN-Na 16177). — Stn CP 1036, 18°01.00’S, 168°48.20’E, 920-950 m, 29.IX.1994, 1 ♂ 8.1 mm (MNHN-Na 16178). — Stn CP 1074, 15°48.42’S, 167°24.27’E, 775-798 m, 4.X.1994, 2 ♀♀ 11.1, 12.7 mm (MNHN-Na 16179). — Stn CP 1075, 15°53.26’S, 167°27.21’E, 956- 944 m, 4.X.1994, 1 ♂ 9.3 mm, 3 ♀♀ 10.0- 13.6 mm (MNHN-Na 16180). — Stn CP 1076, 15°53.81’S, 167°30.42’E, 1100-1191 m, 4.X.1994, 1 ♂ 9.2 mm, 1 ♀ 13.0 mm (MNHN-Na 16181). — Stn CP 1080, 15°57.30’S, 167°27.37’E, 799-850 m, 5.X.1994, 1 ♂ 9.3 mm, 4 ♀♀ 9.5-9.7 mm, 4 ovig. ♀♀ 12.4-13.0 mm (MNHN-Na 16182). — Stn CP 1125, 15°57.63’S, 166°38.43’E, 1160-1220 m, 10.X.1994, 3 ♂♂ 7.7-9.2 mm, 4 ♀♀ 6.1-12.5 mm (MNHN-Na 16183). — Stn CP 1126, 15°58.35’S, 166°39.98’E, 1210-1260 m, 10.X.1994, 3 ♂♂ 8.0- 8.8 mm, 7 ♀♀ 6.0- 13.7 mm (MNHN-Na 16184). — Stn CP 1129, 16°00.73’S, 166°39.94’E, 1014-1050 m, 10.X.1994, 7 ♂♂ 8.4-8.6 mm, 6 ♀♀ 6.4-13.3 mm, 1 ovig. ♀ 10.8 mm (MNHN-Na 16185).

Solomon Islands. SALOMON 1, stn CP 1752, 09°06.9’S, 159°53.2’E, 896-912 m, 25.IX.2001, 1 ♂ 8.8 mm (MNHN-Na 16186). — Stn CP 1754, 09°00.1’S, 159°49.0’E, 1169-1203 m, 26.IX.2001, 1 ♀ 10.6 mm (MNHN-Na 16187). — Stn CP 1755, 8°58.2’S, 159°41.6’E, 1288-1313 m, 26.IX.2001, 1 ♀ 9.1 mm (photographed specimen) (MNHN-Na 16188).— Stn CP 1755, 08°58.2’S, 159°41.6’E, 1288-1313 m, 26.IX.2001, 1 ♂ 9.2 mm, 1 ♀ 11.3 mm (MNHN-Na 16189). — Stn CP 1764, 08°36.6’S, 160°07.4’E, 1327-1598 m, 27.IX.2001, 1 ♂ 8.1 mm (MNHN-Na 16190). — Stn CP 1781, 08°31.2’S, 160°37.7’E, 1036-1138 m, 29.IX.2001, 1♂ 9.0 mm, 3 ♀♀ 10.4-11.2 mm (MNHN- Na 16191). — Stn CP 1807, 09°42.2’S, 160°52.8’E, 1077-1135 m, 2.X.2001, 12 ♂♂ 7.7-9.8 mm, 4 ♀♀ 9.1-14.0 mm (MNHN-Na 16192). — Stn CP 1858, 09°37.0’S, 160°41.7’E, 435-451 m, 7.X.2001, 2 ♂♂ 7.8, 8.3 mm (MNHN-Na 16193).

SALOMON 2, Off Santa Isabel Island, stn CP 2182, 08°47.0’S, 159°37.9’E, 762-1060 m, 22.X.2004, 3 ♀♀ 7.5-11.2 mm (MNHN-Na 16194). — Stn CP 2197, 08°24.4’S, 159°22.5’E, 897-1057 m, 24.X.2004, 1 ♂ 9.1 mm, 5 ♀♀ 8.7-13.1 mm ( CBM-ZC 8604). — Stn CP 2216, 07°45.3’S, 157°39.4’E, 930-977 m, 27.X.2004, 1 ♀ 8.1 mm (MNHN-Na 16195). — Stn CP 2230, 06°27.8’S, 156°24.3’E, 837-945 m, 29.X.2004, 2 ♀♀ 11.9, 13.8 mm (MNHN-Na 16196). — Off Choiseul Island, stn CP 2232, 06°24.1’S, 156°20.4’E, 1045-1207 m, 29.X.2004, 1 ♀ 12.3 mm (MNHN-Na 16197). — South of Taylor reefs, stn CP 2241, 06°55.3’S, 156°21.2’E, 815-1000 m, 30.X.2004, 1 ♀ 10.6 mm (MNHN-Na 16198). — Off Vella Lavella Island, stn CP 2251, 07°27.9’S, 156°14.0’E, 1000-1050 m, 2.XI.2004, 1 ♀ 13.5 mm (MNHN- Na 16199). — Stn CP 2253, 07°26.5’S, 156°15.0’E, 1200-1218 m, 2.XI.2004, 1 ♂ 9.9 mm (MNHN-Na 16200).

OTHER MATERIAL EXAMINED. — Taiwan. TAIWAN 2000, stn CP 32, 22°01.7’N, 120°16.4’E, 904 m, 30.VII.2000, 1 ♂ 8.6 mm ( NTOU). — TAIWAN 2002, stn CD 199, 24°19.27’N, 122°04.21’E, 1138-1187 m, 12. IX.2002, 1 ♂ 8.4 mm, 1 ♀ 15.2 mm ( NTOU). — TAIWAN 2005, stn CP 300, 22°14.55’N, 119°58.71’E, 960-972 m, 11.VIII.2005, 1 ♂ 9.0 mm ( NTOU).

Philippines. MUSORSTOM 1, stn CP 49, 13°49.1’N, 119°59.8’E, 925- 750 m, 25.III.1976, 1 ♀ 10.2 mm (MNHN-Na 5314). — MUSORSTOM 2, stn CP 50,

13°36.7’N, 120°33.7’E, 810-820 m, 27.XI.1980, 2 ♀♀ 9.6, 10.6 mm (MNHN-Na 5317). — Stn CP 55, 13°53.7’N, 119°58.5’E, 865-866 m, 27.XI.1980, 1 ♀ 11.1 mm, 1 ovig. ♀ 12.6 mm (MNHN-Na 5318).

Indonesia. Siboga , stn 88, northern part of Makassar Strait, 00°34.6’N, 119°08.5’E, 1301 m, 20. VI.1899, 2 ♀♀ 6.0, 10.0 mm paralectotypes of Pontophilus occidentalis var. indica de Man, 1918 ( ZMA). — Stn 178, Ceram Sea, 02°40’S, 128°37.5’E, 835 m, 2.IX.1899, 1 ♀ 5.3 mm ( ZMA). — Stn 211, east of Saleyer Island, 05°40.7’S, 120°45.5’E, 1158 m, 25.IX.1899, 1 ♀ 7.0 mm ( ZMA). — CORIN- DON 2 (Makassar Strait), stn CP 231, 00°04.9’N, 119°47.8’E, 1080- 980 m, 4.XI.1980, 1 ♂ 7.6 mm, 4 ♀♀ 5.0- 10.7 mm (MNHN-Na 5322). — Stn CP 240, 00°37.6’S, 119°33.5’E, 675 m, 5.XI.1980, 1 ♀ 8.6 mm (MNHN-Na 5323). — Stn CP 241, 00°57.7’S, 119°15.3’E, 1550- 1525 m, 6.XI.1980, 1 ♂ 9.0 mm, 3 ♀♀ 8.6-9.4 mm (MNHN-Na 5324). — Stn CP 280, 01°59.0’S, 119°09.9’E, 800- 715 m, 8.XI.1980, 1 ♀ 10.2 mm (MNHN-Na 5325). — Stn CP 281, 01°57.5’S, 119°02.0’E, 1150- 1120 m, 8.XI.1980, 1 ♀ 9.5 mm (MNHN-Na 5326).

KARUBAR, Tanimbar Islands, stn CP 52, 08°03’S, 131°48’E, 1244-1266 m, 30.X.1991, 3 ♀♀ 10.4-12.3 mm (MNHN-Na 16202). — Stn CP 87, 08°47’S, 130°49’E, 1017-1024 m, 5.XI.1991, 5 ♀♀ 11.8-13.0 mm (MNHN- Na 16203). — Stn CP 91, 08°44’S, 131°05’E, 884-891 m, 5.XI.1991, 1 ♀ 10.0 mm (MNHN-Na 16204).

New Caledonia. BIOCAL, stn CP 75, 22°19’S, 167°23’E, 825-860 m, 4.IX.1985, 1 ♀ 11.0 mm, 2 ovig. ♀♀ 9.8, 11.0 mm (MNHN-Na 16205).

BATHUS 1, stn CP 651, 21°41.80’S, 166°40.10’E, 1080-1180 m, 11.III.1993, 2 ♂♂ 7.0, 7.3 mm, 2 ♀♀ 9.0, 10.2 mm (MNHN-Na 16206). — Stn CP 660, 21°10.48’S, 165°53.19’E, 786-800 m, 13.III.1993, 3 ♀♀ 10.0- 12.1 mm (MNHN-Na 16207). — Stn CP 661, 21°05’S, 165°50’E, 960-1100 m, 13.III.1993, 1 ♂ 7.7 mm, 1 ♀ 8.4 mm (MNHN-Na 16208).

Tonga. BORDAU 2, stn CP 1565, NW of Tongatapu, 20°58’S, 175°16’W, 869-880 m, 9. VI.2000, 1 ♀ 10.3 mm (MNHN-Na 16209).

ETYMOLOGY. — The specific name difficilis is Latin, meaning difficult, in reference to the difficulty in defining species of the genus.

DISTRIBUTION. — Western Pacific: Taiwan, the Philippines, Indonesia, New Caledonia, Vanuatu and Solomon Islands ( Fig. 35 ), 435-1598 m, and abundant at 800-1100 m.

DESCRIPTION

Rostrum ( Fig.14 A-D) moderately narrow triangular, 0.15-0.17 of carapace length, directed forward or slightly upward, straight, usually not reaching distal margins of corneas; dorsal surface faintly to shallowly concave in proximal half; lateral margins armed with 1 or 2 pairs of small teeth, anterior pair, if present, arising at about midlength of rostrum. Carapace ( Fig. 14 A-D) 1.50-1.80 times longer than wide, with 1 or 2 very small anterior epigastric teeth or denticles; posterior epigastric and cardiac teeth moderately small for genus; postorbital tooth very small, occasionally reduced to minute tubercle; postorbital ridge obsolete; epibranchial ridge low, but usually well-marked; branchiostegal tooth moderately long, slightly falling short of or reaching dorsodistal margin of antennal basicerite.

Third pleonal somite ( Fig. 14E ) with tergum moderately convex and with posterodorsal margin moderately produced. Fifth somite ( Fig. 14F ) rounded on dorsal surface. Sixth somite ( Fig. 14E, F ) 3.30-3.50 times longer than wide, 2.60-2.90 times longer than deep; dorsal surface with trace of submedian ridges flanking faint median sulcus.

Eye ( Figs 14A, D ; 16A ) generally bean-shaped; cornea usually light yellow or opaque, rarely pale brown or gray in preservative; corneal surface distinctly faceted with very small lenses ( Fig. 20E ); maximal diameter of cornea 0.18-0.20 of carapace length; boundary between corneal region and eyestalk rather distinct; eye-stalk slightly constricted near base. Antennular peduncle ( Fig. 14A ) falling short of midlength of antennal scale. Antennal scale ( Fig. 14A ) 0.60-0.80 of carapace length; lateral margin slightly sinuous or slightly concave, distolateral tooth slightly falling short of or reaching distal margin of lamella.

Palm of first pereopod ( Figs 14G , 16D ) 3.80-4.00 times longer than wide; cutting edge moderately oblique; pollex relatively small, width including tip of pollex 1.30-1.40 of width proximal to base of pollex; merus with relatively weak dorsodistal tooth. Second pereopod ( Fig. 16F ) short, reaching or falling short of midlength of merus of first pereopod. Fourth pereopod ( Figs 14H ; 16I ) overreaching distal margin of antennal scale by half to full length of dactylus; dactylus subspatulate, 0.50-0.65 of propodal length; carpus 0.70-0.80 of propodal length. Fifth pereopod ( Fig. 16J ) similar to fourth, slightly falling short of distal margin of antennal scale. Appendix masculina of male second pleopod ( Fig. 15L ) 0.50-0.70 length of appendix interna.

Coloration in life

Body entirely reddish-brown, occasionally slightly darker in anterior part of carapace and first pereopods. Cornea of eye gold.

Size

Males CL 6.4-13.3 mm; females CL 5.0-14.0 mm, ovigerous females CL 9.8-13.0 mm.

REMARKS

The rostrum is usually armed with two pairs of lateral teeth, but either or both of the anterior pairs are sometimes missing like in most of the other species of the group.

This new species appears close to Parapontophilus junceus and P. geminus n. sp. Differentiating characters among the three species are discussed under Remarks of the latter respective species.

For the discussion on the synonymy, see the Remarks of P. junceus .

Figures

FIG. 6. — A, B, Parapontophilus junceus (Bate, 1888);C, Parapontophilus difficilis n. sp.; A, ♀ 8.2 mm,holotype of Pontophilus junceus Bate, 1888, Moro Gulf, Mindanao, Philippines (Challenger, stn 200) (NMH 1888.22), anterior part of carapace and eyes, dorsal view (distal part of rostrum broken off; dotted line showing reconstruction); B, ♀ 8.6 mm, lectotype of Pontophilus occidentalis var. indica de Man, 1918, Bali Sea, Indonesia (Siboga, stn 316) (ZMA), anterior part of carapace, eye and basal part of antennae, lateral view; C, ♀ 7.0 mm, paralectotype of Pontophilus occidentalis var. indica de Man, 1918, 7.0 mm, east of Saleyer Island (Siboga, stn 211) (ZMA), same part. Scale bars: 2 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.

FIG. 15. — Parapontophilus difficilis n. sp.: A, thoracic sternum, ventral view (setae omitted); B, first segment of left antennular peduncle, ventral view; C, left antenna, ventral, view; D, left mandible, inner view; inset, details of distal part; E, left maxillule, outer view; F, left maxilla, outer view; G, left first maxilliped, outer view; H, left second maxilliped, outer view; I, K, left first pleopod, ventral view; J, endopod of left first pleopod, ventral view; L, appendix masculina and appendix interna of left second pleopod, mesial view; M, left uropod, dorsal view; A, I, J, L, ♂ 9.8 mm, paratype, Solomon Islands (SALOMON 1, stn CP 1807) (MNHN-Na 16192); B-H, K, M, ♀ 11.1 mm, paratype, same lot. Scale bars: A, B, F-I, K, 1mm; C, M, 2 mm; D, E, J, L, 0.5 mm.

FIG. 16. — Parapontophilus difficilis n. sp., ♀ 11.1 mm, paratype, Solomon Islands (SALOMON 1, stn CP 1807) (MNHN-Na 16192): A, left eye, ventromesial view; B, left third maxilliped, lateral view; C, same, dorsal view (most setae omitted); D, right first pereopod, lateral view;E, rudimentary exopod of third maxilliped;F, right second pereopod,lateral view; G, same,chela and carpus,lateral view; H, right third pereopod, lateral view;I, right fourth pereopod,lateral view; J, right fifth pereopod,lateral view;K, dactylus of right fourth pereopod, dorsal view; L, same, details of tip. Scale bars: A, 1 mm; B-D, F, H-J, 2 mm; E, G, K, L, 0.5 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) (✚).