Prionocrangon demani, Kim & Chan, 2005

Kim, Jung Nyun & Chan, Tin-Yam, 2005, A revision of the genus Prionocrangon (Crustacea: Decapoda: Caridea: Crangonidae), Journal of Natural History 39 (19), pp. 1597-1625 : 1617-1620

Prionocrangon demani sp. nov.

( Figure 9 )

Prionocrangon ommatosteres: de Man 1920, p 308 , Plate 25 Figure 76, 76a–i [non Wood- Mason and Alcock, 1891]

? Prionocrangon ommatosteres: Chace 1984, p 56 (key), 58 [non Wood-Mason and Alcock, 1891].

Material examined

Philippines. Sulu Sea, RV Hakuho-Maru, KH-02-4 Cruise, stn 14, 10 ° 00.709– 10 ° 01.629N, 120 ° 54.729– 120 ° 55.279E, 1482–1488 m, 8 December 2002, 1 „ (CL 4.1 mm), holotype, CBM-ZC 7841 .

Indonesia. Albatross stn 5637, off south of Buru, 3 ° 539200S, 126 ° 489000E, 1280 m, 10 December 1909, Agassiz beam trawl, 1♀ without carapace, paratype, USNM 205088 (referred to ‘‘? P. ommatosteres ’’ in Chace 1984) .

Description

Rostrum reaching tip of branchiostegal spine, 0.11–0.16 times as long as carapace ( Figure 9A ). Mid-dorsal carina of carapace armed with six to eight spines ( Figure 9A ). Fourth and fifth abdominal somites without median carina; sixth somite 0.60 times as long as carapace, posterior margin of posterolateral process subtruncate, lacking minute denticle but slightly produced ventrally ( Figure 9E ). Telson slightly longer than sixth abdominal somite ( Figure 9D ), 0.64 times as long as carapace, posterior half slightly convergent; posterior margin subtruncate, armed with two pairs of long spines and with or without minute median denticle ( Figure 9F ). Eyestalks triangular, drawn out to subacute extremities, lateral margin slightly sinuous ( Figure 9C ). Antennular peduncle with proximal segment moderately long, 0.61 times as long as carapace ( Figure 9B ). Stylocerite with tip elongate and sharp ( Figure 9C ). Scaphocerite overreaching proximal segment of antennular peduncle, 0.67 times as long as carapace ( Figure 9B ). Palm of first pereopod moderately stout, 4.45–4.48 times as long as wide ( Figure 9G ). Dactyli of fourth and fifth pereopods relatively long, 0.65–0.79 times as long as propodi ( Figure 9H ). Females with endopod of second pleopod about 0.25 times as long as exopod ( Figure 9I ); endopods and protopods of second to fifth pleopods with small proximolateral lobe and distoventral projection, respectively ( Figure 9J ).

Size

The two males known are CL 4.1 and 6.4 mm, the only intact female is CL 7.5 mm ( de Man 1920; present study).

Distribution

Indonesia and the Philippines, at depths of 1158–1488 m.

Colour in life

Not known.

Etymology

The species is named after J. G. de Man for his important contributions to the taxonomy of the Crangonidae and for providing detailed illustrations on the ‘‘Siboga’’ material of this form.

Remarks

Although attempts to borrow the two Indonesian specimens reported by de Man (1920) as P. ommatosteres from the Zoological Museum of Amsterdam were unsuccessful, the detailed illustrations given by de Man (1920, Plate 25 Figure 76, 76a–i) show that the ‘‘Siboga’’ material is not true P. ommatosteres but actually belongs to the present new species. P. demani is most similar to P. pectinata except in having a longer and less convergent telson. Moreover, females of P. demani have the second to fifth pleopods with a small proximolateral lobe on the endopods and a small distoventral projection on the protopods, while these lobes and projections are absent in P. pectinata .

The badly damaged female collected by the Albatross and tentatively assigned to P. ommatosteres by Chace (1984) has triangular eyestalks, a longer and less convergent telson, the dactyli of the last two pereopods are rather long, and the posterolateral process of the sixth abdominal somite is only produced ventrally. All these characters show that this specimen is P. demani .

Figures

Figure 9. Prionocrangon demani sp. nov. (A–H, K) holotype male (CL 4.1 mm) from Sulu Sea, the Philippines, KH-02-04 Cruise stn 14; (I, J) paratype female from Indonesia off south of Buru, Albatross stn 5637. (A) Carapace (tip of rostrum broken) with cephalic and thoracic appendages, lateral; (B) carapace (tip of rostrum broken) and anterior cephalic appendages, dorsal; (C) anterior part of carapace (tip of rostrum broken), eyes, basal parts of antennule and antenna, dorsal; (D) posterior part of abdomen and tailfan, lateral; (E) posterolateral process of sixth abdominal somite, lateral; (F) posterior part of telson, dorsal; (G) chela of left first pereopod, ventral; (H) dactylus and propodus of right fourth pereopod, lateral; (I) left second pleopod, ventral; (J) endopod and distal part of protopod of right second pleopod, mesial; (K) appendix masculina of left second pleopod, mesial.