Parapontophilus psyllus, 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 : 319-322

Parapontophilus psyllus n. sp.

( Figs 28 ; 29 )

TYPE MATERIAL. — Holotype: Japan. TV Toyoshiomaru, 2005-04 cruise, stn 6, off Nago, Okinawa Island , Ryukyu Islands , 26°32.90’N, 127°43.94’E, 396-407 m, 22.V.2005, beam trawl, coll. T. Komai, ovig. ♀ 4.6 mm ( CBM-ZC 8762 ).

Paratypes: Japan. TV Toyoshio-maru, 2002-05 cruise,stn 11, off Nago Bay, Okinawa Island, Ryukyu Islands, 26°32.18’N, 127°43.96’E, 404- 394 m, 27. V.2002, coll. H. Komatsu, 5 ♂♂ 3.7-3.8 mm, 11 ovig. ♀♀ 3.7-4.0 mm ( CBM-ZC 8028). — Same data as holotype, 7 ♂♂ 3.7-3.9 mm, 6 ovig. ♀♀ 3.7-4.2 mm ( CBM-ZC 8763).

Taiwan. TAIWAN 2001, stn CC 63, 24°55.05’N, 122°03.20’E, 240-350 m, 5. V.2001, 1 ♀ 4.2 mm ( NTOU).

OTHER MATERIAL EXAMINED. — Philippines. MUSORSTOM 1, stn CP 20, 13°59.2’S, 120°20,3’E, 208-222 m, 21.III.1976, 1 ovig. ♀ 4.2 mm (MNHN-Na 16075).

Solomon Islands. SALOMON 1, stn CP 1860, 09°22’S, 160°31’E, 620 m, 7.X.2001, 1 ♂ 3.9 mm (MNHN-Na 16079).

ETYMOLOGY. — From the Greek psyllus , flea, in reference to the small size of this new species. The name is considered as a substantive in apposition.

DISTRIBUTION. — Ryukyu Islands, Taiwan, the Philippines and Solomon Islands ( Fig. 36 ), 208- 620 m.

DESCRIPTION

Rostrum ( Fig. 28 A-C) narrow triangular in dorsal view, 0.15-0.18 of carapace length, directed forward, straight, slightly falling short of distal margins of corneas, but slightly overreaching tips of antennal teeth; lateral margins always armed with 1 pair of small to tiny teeth arising at about midlength of rostrum. Carapace ( Fig. 28A, B, D ) 1.30-1.40 times longer than wide; anterior epigastric tooth greatly reduced to minute denticle or absent; posterior epigastric tooth small, supported by blunt middorsal ridge reaching beyond midlength of carapace; cardiac tooth absent; postorbital tooth reduced to minute tubercle or absent; epibranchial tooth absent; epibranchial ridge obsolete or absent; branchiostegal tooth small, not reaching dorsodistal margin of antennal basicerite.

Third pleonal somite ( Fig. 28E ) with moderately convex tergum and with moderately produced posterodorsal margin. Fifth somite ( Fig. 28E, F ) round- ed dorsally. Sixth somite ( Fig. 28E, F ) 2.90-3.00 times longer than wide, 2.20-2.50 times longer than deep, 2.00-2.20 length of fifth somite; dorsal surface rounded.

Ophthalmic appendage ( Fig. 28A ) subpyriform; cornea pigmented with light brown or gray in preservative; corneal surface distinctly faceted with moderately small lenses; maximal diameter of cornea 0.15-0.17 of carapace length; eye-stalk constricted near base; mesial face without papilla-like projection. Antennular peduncle ( Fig. 28A ) reaching midlength of antennal scale. Antennal scale ( Fig. 28A ) about 0.60-0.65 of carapace length and 2.72-2.90 times longer than wide; lateral margin nearly straight or slightly concave, lamella strongly produced, distinctly overreaching distolateral tooth.

Palm of first pereopod ( Fig. 29A, B ) 3.10-3.40 times longer than wide; pollex moderately produced, width including tip of pollex about 1.30 of width of palm proper; cutting edge moderately oblique; merus with relatively weak dorsodistal tooth. Second pereopod ( Fig. 29C ) relatively long for genus, overreaching midlength of merus of first

D

A pereopod. Fourth pereopod ( Fig. 29E ) overreaching distal margin of antennal scale by half to full length of dactylus; dactylus elongate, subspatulate, 0.80-0.95 of propodal length; carpus 0.50-0.65 of propodal length. Fifth pereopod similar to fourth, slightly falling short of distal margin of antennal scale. Appendix masculina of male second pleopod ( Fig. 29F ) 0.85-0.90 length of appendix interna.

Coloration in life

Body entirely light reddish-brown; corneas dark gray (based on field note by the author).

Size

Males CL 3.7-3.9 mm; females CL 3.7-4.6 mm, ovigerous females CL 3.7-4.6 mm.

REMARKS

In P. psyllus n. sp., the size of the branchiostegal tooth of the carapace seems to be different between male and female. In males, this tooth nearly reaches the dorsodistal margin of the antennal basicerite, whereas in females, it falls short of that.

This new species is characteristic within the species group in the possession of only one pair of lateral teeth on the rostrum, rather than two pairs in the other species of the group ( Table 2). Furthermore, in P. psyllus n. sp., the anterior epigastric tooth is absent or rudimentary and the postorbital tooth is absent. In the other species of the group, the anterior epigastric and postorbital teeth are conspicuous, although the sizes of these teeth are different according to species.

Figures

FIG. 28. — Parapontophilus psyllus n. sp., ovig. ♀ 4.6 mm, holotype, off Nago, Okinawa Island, Ryukyu Islands (TV Toyoshio-maru, 2005-04 cruise, stn 6) (CBM-ZC 8762): A, carapace and cephalic appendages, dorsal view; B, carapace, lateral view; C, rostrum dorsal view; D, anterior part of carapace, eye and basal part of antennae, lateral view; E, third to sixth pleonal somites, lateral view; F, fourth to sixth pleonal somites and telson, dorsal view. Scale bars: A, B, D-F, 1 mm; C, 0.5 mm.

FIG. 29. — Parapontophilus psyllus n. sp., left appendages: A, first pereopod, lateral view; B, same, subchela, ventral view; C, second pereopod,lateral view;D, third pereopod,lateral view;E, fourth pereopod, lateral view; F, appendix masculina and appendix interna of left second pleopod,mesial view; A-E, ovig.♀ 4.6 mm,holotype,off Nago,Okinawa Island,Ryukyu Islands (TV Toyoshio-maru, 2005-04 cruise, stn 6) (CBM-ZC 8762); F, ♂ 3.8 mm, paratype, same data as holotype (CBM-ZC 8763). Scale bars: A-E, 1 mm; F, 0.5 mm.

FIG. 36.— Geographic distribution of Parapontophilus demani (Chace,1984) (●), P. caledonicus n. sp. (▼), P. juxta n. sp. (▲), P. modumanuensis (Rathbun, 1906) (◆), P. psyllus n. sp. (✖), P. sibogae n. sp. (■), and P. stenorhinus n. sp. (✚).