Prionocrangon paucispina, 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 : 1620-1623

Prionocrangon paucispina sp. nov.

( Figures 10 , 11C )

Material examined Taiwan. TAIWAN 2002, ‘‘ Ocean Researcher 1’’, stn CP 183, 21 ° 58.229N, 119 ° 27.999E ,

2519–2556 m, 26 August 2002, 2♀♀ (CL 4.4 mm, other one abdomen only), paratypes, NTOUM00594; stn CP 185, 22 ° 0.549N, 119 ° 27.949E, 2334–2543 m, 26 August 2002, 1 „ (CL 7.6 mm), holotype, NTOUM00592, 1 „ (CL 7.2 mm), 2♀♀ (CL 5.8, 8.1 mm, large one with bopyrid parasite probably Eragia profunda attached on abdomen), paratypes, NTOUM00593.

New Caledonia. BIOCAL, stn CP 72, 22 ° 109S, 167 ° 339E, 2100–2110 m, 4 September 1985, 2♀ (CL 8.8, 9.0 mm, small one bearing the holotype of the bopyrid parasite Eragia profunda Markham, 1994 ), paratypes, MNHN-Na. 15070. BIOGEOCAL, stn CP 273, 21 ° 019530S, 166 ° 579410E, 1920–2040 m, 20 April 1987, 1♀ (CL 8.0 mm), paratype, MNHN-Na. 15071 .

Description

Rostrum extending slightly beyond tip of antennal spine, 0.08–0.10 times as long as carapace ( Figure 10A ). Mid-dorsal carina of carapace armed with four to five spines ( Figure 10A ). Fourth and fifth abdominal somites without median carina; sixth somite 0.58–0.70 times as long as carapace, posterior margin of posterolateral process subtruncate, usually with median excavation as well as dorsal and ventral minute denticles or blunt processes ( Figure 10F, G , rarely median excavation and/or denticles indistinct). Telson slightly longer than sixth abdominal somite ( Figure 10E ), 0.69–0.72 times as long as carapace, posterior half slightly convergent ( Figure 10H ); posterior margin rounded, armed with 10–13 long spines and without median denticle ( Figure 10J ). Eyestalks triangular, shortly drawn out to blunt extremities, lateral margin slightly sinuous ( Figure 10C ). Antennular peduncle with proximal segment relatively short, 0.53–0.59 times as long as carapace ( Figure 10B ). Stylocerite broadly triangular, with tip stout (rarely with minute denticle) and not protruded ( Figure 10C, D ). Scaphocerite extending to second segment of antennular peduncle, 0.57–0.70 times as long as carapace ( Figure 10B ). Palm of first pereopod relatively stout, 3.87–4.48 times as long as wide ( Figure 10K ). Dactyli of fourth and fifth pereopods short, 0.41–0.46 times as long as propodi ( Figure 10L ). Adult females (more than CL 8.0 mm) with endopod of second pleopod about 0.40 times length of exopod ( Figure 10M ). Females with endopods and protopods of pleopods without lateral lobe or distoventral projection ( Figure 10M ).

Size

Males CL 7.2–7.6 mm, females CL 4.4–9.0 mm.

Distribution

Taiwan and New Caledonia, at depths of 1920–2556 m.

Colour in life

Body generally ivory white and somewhat translucent. Internal organs visible inside carapace as greenish brown ( Figure 11C ).

Variations

Of the nine specimens examined: the three specimens from New Caledonia all have four dorsal carapace spines while the five specimens from Taiwan with carapace all have five dorsal spines. The tip of the stylocerite is obscure ( Figure 10C ) in two specimens but clearly defined ( Figure 10D ) in six specimens. Of the five specimens still with intact telsons, three bear 10 long posterior spines ( Figure 10I ) and one has 12 posterior spines and one has 13 posterior spines ( Figure 10J ) .

Etymology

The Latin paucispina refers to the fewer dorsal carapace spines in this species.

Remarks

Although from rather disjunct localities, the present Taiwanese and New Caledonian material agree well with each other. The only difference observed is the number of dorsal carapace spines, being four in all three New Caledonian specimens and five in the five intact Taiwanese specimens. The short rostrum, low number of dorsal carapace spines, triangular eyestalks drawn out slightly to form blunt extremities, a stylocerite in which the tip is not elongate ( Figure 10C, D ), and the posterolateral process on the sixth abdominal somite usually bearing a median excavation and dorsal and ventral denticles or blunt processes ( Figure 10F, G ), easily distinguish the present form from congeners. Moreover, this form has a much deeper known bathymetric range (1920–2556 m deep) than the other species (at depths of less than 1488 m). There is little doubt that this deep-water form is an undescribed species and warrants a new name.

The female abdomen from TAIWAN 2001 stn CP 183 lacks a median carina on the abdomen and has 12 long posterior spines on the telson, and was collected from very deep waters together with a small female P. paucispina . Therefore, it is clear that this abdomen is not P. dofleini or P. formosa and can be safely considered as representing P. paucispina .

Figures

Figure 10. Prionocrangon paucispina sp. nov. (A–C, E, F, H, I, K–M) Paratype female (CL 9.0 mm) from New Caledonia, BIOCAL stn CP 72; (D) paratype male (CL 7.2 mm) from Taiwan, TAIWAN 2002 stn CP 185; (G) paratype female (CL 8.0 mm) from New Caledonia, BIOGEOCAL stn CP 273; (J) paratype female (CL 5.8 mm) from Taiwan, TAIWAN 2002 stn CP 185; (N) holotype male (CL 7.6 mm) from TAIWAN 2002 stn CP 185. (A) Carapace with cephalic and thoracic appendages, lateral; (B) carapace and anterior cephalic appendages, dorsal; (C, D) anterior part of carapace, eyes, basal parts of antennule and antenna, dorsal; (E) posterior part of abdomen and tailfan, lateral; (F, G) posterolateral process of sixth abdominal somite, lateral; (H) telson, dorsal; (I, J) posterior part of telson, dorsal; (K) chela of right first pereopod, ventral; (L) dactylus and propodus of left fourth pereopod, lateral; (M) left second pleopod, ventral; (N) appendix masculina of left second pleopod, mesial.

Figure 11. (A) Prionocrangon dofleini Balss, 1913, ovigerous female (CL 8.2 mm) from Taiwan (TAIWAN 2001 stn CP 102); (B) Prionocrangon formosa sp. nov., holotype female (CL 4.9 mm) from Taiwan (TAIWAN 2001 stn CP 104); (C) Prionocrangon paucispina sp. nov., holotype male (CL 7.6 mm) from Taiwan (TAIWAN stn CP 185).