Parapontophilus cyrton, 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 : 295-297

Parapontophilus cyrton n. sp.

( Fig. 13 )

TYPE MATERIAL. — Holotype: New Caledonia. BIO- CAL, stn CP 69, 23°52’S, 167°58’E, 1220-1225 m, 3.IX.1985, ♀ 12.6 mm (MNHN-Na 16162).

Paratypes: New Caledonia. BIOCAL, stn CP 27, 23°06’S, 166°26’E, 1850-1900 m, 28.VIII.1985, 1 ♀ 6.7 mm (MNHN-Na 16163). — Stn CP 57, 23°44’S, 166°58’E, 1490-1620 m, 1.IX.1985, 1 ♂ 6.2 mm, 1 ♀ 10.2 mm (MNHN-Na 16164). — Stn CP 58, 23°56’S, 166°41’E, 2660-2750 m, 1.IX.1985, 2 ♀♀ 9.0, 10.4 mm (MNHN-Na 16165). — Stn CP 60, 24°01’S, 167°08’E, 1480-1530 m, 2.IX.1985, 1 ♂ 6.0 mm, 4 ♀♀ 7.1-10.0 mm (MNHN-Na 16166). — Stn CP 62, 24°19’S, 167°49’E, 1395-1410 m, 2.IX.1985, 2 ♀♀ 9.5, 12.5 mm (MNHN-Na 16167). — Stn CP 69, 23°52’S, 167°58’E, 1220-1225 m, 3.IX.1985, 1 ♀ 10.6 mm (MNHN-Na.16168). — Stn CP 72, 22°10’S, 167°33’E, 2100-2110 m, 4.IX.1985, 3 ♀♀ 5.7-7.5 mm (MNHN-Na 16169).

BIOGEOCAL, stn CP 214, 22°43.09’S, 166°27.19’E, 1665- 1590 m, 9.IV.1987, 2 ♂♂ 7.1, 9.0 mm, 2 ♀♀ 7.7, 9.7 mm (MNHN-Na 16170). — Stn CP 265, 21°04.09’S, 167°00.40’E, 1760-1870 m, 18.IV.1987, 1 ♂ 8.1 mm, 1 ♀ 8.1 mm (MNHN-Na 16171). — Stn CP 272, 21°00.04’S, 166°56.94’E, 1615-1710 m, 20.IV.1987, 1 ♀ 11.1 mm (MNHN-Na 16172).

HALIPRO 2, stn BT 77, Norfolk Ridge, 24°09’S, 167°47’E, 1349-1350 m, 21.XI.1996, 1 ♀ 11.0 mm (MNHN-Na 16173).

ETYMOLOGY. — The Greek kyrton (humpback) refers to the strongly geniculate pleon, showing a humpback appearance.

DISTRIBUTION. — Known only from waters around New Caledonia ( Fig. 35 ), 1220-2750 m.

DESCRIPTION

Rostrum ( Fig. 13 A-D) moderately broad, triangular in dorsal view, 0.15-0.18 of carapace length, directed forward and straight, slightly falling short of or reaching distal margins of corneas; dorsal surface shallowly concave in proximal half; lateral margins armed with 1 or 2 pairs of lateral teeth proximal to midlength. Carapace ( Fig. 13 A-D) 1.50-1.70 longer than wide; anterior epigastric tooth distinctly smaller than posterior epigastric tooth; posterior epigastric and cardiac teeth moderately small; postorbital tooth very small, occasionally reduced to minute tubercle; postorbital ridge low, sometimes obsolete; epibranchial ridge low, but usually well-marked; branchiostegal tooth nearly reaching dorsodistal margin of antennal basicerite.

Third pleonal somite ( Fig. 13E ) with tergum somewhat elevated in midline in posterior part and with posterodorsal margin strongly produced, and thus pleon markedly geniculate. Fifth pleonal somite ( Fig. 13E ) smooth on dorsal surface. Sixth pleonal somite ( Fig. 13E, F ) 3.50-3.80 times longer than wide, 2.60-2.90 times longer than deep, dorsal surface with trace of submedian ridges and faint median sulcus; lateral margins slightly concave.

Eye ( Fig. 13D ) generally bean-shaped; cornea white or opaque in preservative, semispherical; corneal surface not faceted, but white granules possibly representing remnants of lenses visible throughout integument of cornea as in P. abyssi ; maximal diameter of cornea 0.15-0.18 of carapace length; boundary between cornea and eye-stalk obscurely delineated; eye-stalk slightly constricted near base. Antennular peduncle ( Fig. 13A ) falling short of midlength of antennal scale. Antennal scale ( Fig. 13A ) 0.70-0.80 of carapace length, 4.00-4.50 times longer than wide; lateral margin slightly concave or nearly straight, distolateral tooth reaching or slightly overreaching distal margin of lamella ( Fig. 13G ).

First pereopod overreaching distal margin of antennal scale by 0.15-0.20 length of palm; palm ( Fig.13H ) 3.80-4.00 times longer than wide; cutting edge moderately oblique; pollex moderately 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 short, reaching or falling short of midlength of merus of first pereopod. Fourth pereopod ( Fig. 13I ) overreaching distal margin of antennal scale by half to full length of dactylus; dactylus subspatulate, 0.50-0.60 of propodal length; carpus 0.80-0.85 of propodal length. Fifth pereopod similar to fourth, slightly falling short of distal margin of antennal scale. Appendix masculina of male second pleopod 0.70-0.80 of appendix interna.

Coloration in life

Body and pereopods entirely pale reddish-brown.

Size

Males CL 6.0-9.0 mm; females CL 5.7-11.1 mm.

REMARKS

The rostrum is usually armed with two pairs of lateral teeth, but either or both of the anterior pairs are rarely missing.

This new species appears close to Parapontophilus abyssi , P. occidentalis and P. talismani . These four species have a conspicuous anterior epigastric tooth and the non-faceted cornea. Parapontophilus cyrton n. sp. is characteristic in having the strongly produced posterodorsal margin of the third pleonal tergite. This makes a condition that the pleon is strongly geniculate. The pollex of the first pereopod is less produced in P. cyrton n. sp. than in the other three species (cf. Fig. 13H and Figs 4I , 8J , 9G ). Furthermore, the anterior epigastric tooth on the carapace is distinctly smaller than the posterior epigastric tooth in P. cyrton n. sp., rather than usually subequal in the latter three species. The distolateral tooth of the antennal scale slightly overreaches the distal margin of the lamella in P. cyrton n. sp., rather than falling short of or nearly reaching it in the other three species. The present new species is also similar to P. difficilis n. sp. in having opaque or yellowish eyes and a small anterior epigastric tooth on the carapace. However, the structure of the third pleonal tergite and the non-faceted cornea distinguish P. cyrton n. sp. from P. difficilis n. sp. In P. difficilis n. sp., the posterodorsal margin of the third pleonal tergite is moderately produced; the cornea of the eye is distinctly faceted. The more produced distolateral tooth of the antennal scale also distinguishes P. cyrton n. sp. from P. difficilis n. sp.

Figures

FIG. 13. — Parapontophilus cyrton n. sp.,♀ 12.6 mm, holotype, New Caledonia (BIOCAL, stn CP 69) (MNHN-Na 16162): 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, third to sixth pleonal somites, lateral view; F, sixth pleonal somite, dorsal view; G, distal part of left antennal scale, dorsal view. Scale bars: A-F, H, 2 mm; G, 1mm.

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. 4. — A-D, Parapontophilus abyssi (Smith, 1884), ♀ 16.2 mm, holotype of Pontophilus gracilis Bate, 1888, near Tristan da Cunha, southwestern Atlantic (Challenger, stn 133) (BMNH 1888.22); A, anterior part of carapace, cornea and basal part of antennae, lateral view;B, sixth pleonal somite, lateral view;C, subchela of left first pereopod,ventral view;D, rostrum, dorsal view;E-I, Parapontophilus sp., ♀ 10.8 mm,paratype of Pontophilus challengeri Ortmann, 1893, Celebes Sea (Challenger, stn 198) (BMNH 1888.22),E, carapace and cephalic appendages, dorsal view; F, anterior part of carapace, cornea and basal part of antennae, lateral view; G, rostrum and left eye, dorsal view; H, sixth pleonal somite, lateral view; I, subchela of first pereopod, ventral view. Scale bars: A, B, D, E, 2 mm; C, H, 5 mm; F, G, I, 1 mm.

FIG. 8. — Parapontophilus occidentalis (Faxon, 1893), ♀, 18.5 mm, syntype, Gulf of Panama, eastern Pacific (Albatross, stn 3382) (MZC 4584):A, carapace and cephalic appendages, dorsal view (setae partially omitted); B, carapace, lateral view; C, anterior part of carapace, cornea, and basal part of antennae, lateral view; D, anterior part of carapace and eye, dorsal view; E, third to fifth pleonal somite, lateral view; F, fifth pleonal somite, dorsal view; G, sixth pleonal somite, lateral view; H, same, dorsal view; I, distal part of left antennal scale, dorsal view; J, subchela of right first pereopod, ventral view. Scale bars: A, B, D-H, 5 mm; C, I, J, 2 mm.

FIG. 9.— Parapontophilus talismani (Crosnier & Forest,1973):A, carapace and cephalic appendages,dorsal view (setae partially omitted); 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, sixth pleonal somite, lateral view; F, left eye, ventromesial view; G, subchela of right first pereopod, ventral view; A-E, G, ovig. ♀ 9.8 mm, Bay of Biscay (BIOGAS, stn CV 26) (MNHN-Na 4325); F, ovig. ♀ 9.0 mm, Bay of Biscay (POLYGAS, stn CV 12) (MNHN-Na 4324). Scale bars: A-E, G, 2 mm; F, 1 mm.