Periclimenaeus gorgonidarum

Host. Balss (1913, 1914) reported that the type specimen was collected with an unidentified gorgonian (Cnidaria: Alcyonacea) from Sagami Bay (Japan). Fransen (1994) also collected this species on an unidentified gorgonian of the family Melithaeidae in the Seychelles. These are however considered incidental associations, possibly from encrusting sponges, as all other records in literature are from pipe sponges in the genera Callyspongia and Siphonochalina (Porifera: Callyspongiidae) (Bruce 1976, 1981; Kim & Kim 1985; Marin 2012; Marin & Caley 2011; Miyake & Fujino 1967). All Korean specimens reported herein were collected from the spongocoel of C. cf. confoederata (Fig. 7 A and C), together with Onycocaris callyspongiae Fujino & Miyake, 1969 which was found inside a channel of the sponge wall (Fig. 7 B). The Taiwanese specimen was collected from Callyspongia sp. (Porifera: Callyspongiidae), whilst the Chagos specimen was obtained from an unidentified encrusting sponge. Ise (2017) drew attention to the fact that Japanese records of C. confoederata are likely a different species from the true C. confoederata (Ridley, 1884) described from the Torres Straits (northern Australia). The true host identity of P. gorgonidarum thus remains unknown, as indeed the question as to whether it inhabits several sponge species or even genera in Callyspongiidae.

Sumber: On the systematic status of Isopericlimenaeus Marin, 2012 and its type species, Periclimenaeus gorgonidarum (Balss, 1913) (Crustacea: Decapoda Palaemonidae)

Description. Body medium-sized, subcylindrical form (Fig. 2). Rostrum (Figs. 3 A, 5 B) straight, horizontal, about 0.55 of pocl, reaching slightly beyond end of antennular peduncle, 6 – 10 dorsal teeth along entire length, 1 – 3 subterminal ventral tooth, ventral margin straight. Carapace (Figs. 3 A, 5 A) smooth, glabrous, without hepatic tooth; supraorbital and antennal teeth acute; inferior orbital angle with small blunt process (Figs. 3 B, 5 A); anterolateral pterygostomial angle rounded. Abdomen smooth, first segment without anteromedian dorsal lobe (Fig. 2); pleura broadly rounded, sixth segment subequal to fifth, posterolateral angle with minute tooth on each side, posteroventral angle acute (Figs. 3 C, 5 C and D). Telson (Figs. 3 C, 5 D) 0.65 – 0.70 of pocl, about 2 times longer than maximum width; two pairs of dorsal spiniform setae at about 0.1 and 0.5 of telson length respectively, proximal pair (Fig. 3 I) almost 2.5 – 3.0 times longer than posterior ones; posterior margin with minute median tooth, lateral posterior spiniform setae short, 0.25 – 0.35 of length of intermediate pair, intermediate pair long and stout, submedian pair 0.85 – 0.95 of intermediate pair length (Figs. 3 C, 5 E). Eye (Fig. 3 D) with hemispherical cornea, with nebenauge; stalk 1.0 – 1.3 times longer than wide. Antennule (Fig. 3 E) with proximal peduncle bearing acute distolateral tooth, with acute tooth at ventromedial margin; stylocerite broad, bearing short sharp point, reaching to 0.35 – 0.40 times of proximal segment; intermediate segment short, 0.30 – 0.35 times of proximal segment length, subequal to distal segment; upper flagellum biramous, proximal four segments fused, lower flagellum slender, filiform. Antenna (Fig. 3 F) basicerite with blunt distodorsal margin; ischiocerite and merocerite unarmed; carpocerite reaching to about 0.70 of scaphocerite length; scaphocerite 1.70 – 1.90 times as long as maximum width, lateral margin straight, anterior margin slightly rounded, medial margin convex, distolateral tooth large, overreaching end of lamella. Mouthparts not dissected. Third maxilliped (Fig. 3 G) slightly overreaching end of carpocerite; ultimate segment about 0.40 times antepenultimate segment, tapering distally, with dense tufts of long setae; penultimate segment about 0.50 times antepenultimate segment, with ventromedial row of long setae; antepenultimate segment with long setae on ventromedial margin; exopod overreaching antepenultimate segment, distally with four plumose setae. First pereiopod (Figs. 2, 4 E, 5 F) long, slender, overreaching distal end of scaphocerite by one third of merus; fingers simple, short 0.34 – 0.40 of palm length; carpus subequal to merus length, with simple setae; ischium subequal to chela length, basis and coxa without special features. Second pereiopods robust, dissimilar in shape, unequal in size. Major second pereiopod (Figs. 4 A, C and 6 A, B) overreaching distal end of scaphocerite by middle of carpus; chela 3.2 – 4.0 times as long as merus; fingers 0.40 – 0.60 of palm length; dactylus distally curved, with blunt tip, cutting edge centrally with molar process; fixed finger distally curved with blunt tip, cutting edge distally entire, centrally with deep oval fossa and one blunt tooth; palm subcylindrical, minutely tuberculate along entire margin; carpus overlapping proximal part of palm; merus 1.20 – 1.60 of ischium length; merus and ischium with minute and subacute tubercles along ventral margin. Minor second pereiopod (Korean specimens; Fig. 4 B, D) slightly shorter than major; chela less than about 3.0 – 3.6 times as long as merus; fingers 0.55 – 0.65 of palm; dactylus distally curved, with pointed tip, cutting edge centrally with molar process; fixed finger distally curved with blunt tip, cutting edge distally entire, centrally with deep oval fossa and one blunt tooth; palm subcylindrical, minutely tuberculate along entire margin; carpus overlapping proximal part of palm; merus with minute tubercles along ventral margin. Minor second pereiopod (Taiwanese specimen; Fig. 6 C, D) overreaching distal end of scaphocerite by end of merus; chela less than 2.44 times as long as merus; fingers about 0.87 of palm; dactylus distally curved, with pointed tip, cutting edge entire, unarmed; fixed finger distally curved, cutting edge entire, with one pointed tooth at proximal 0.18; palm subcylindrical; carpus overlapping proximal part of palm; merus and ischium with minute and subacute tubercles along ventral margin. Ambulatory pereiopods subequal in shape, third pereiopod slightly longer than fourth and fifth (Fig. 2). Third pereiopod (Figs. 4 F, 5 G) overreaching distal end of scaphocerite by distal half of carpus, propodus and dactylus; dactylus short, biunguiculate, with serrated ventral margin (Figs. 4 G, 5 H); propodus about 5.0 of dactylus length, with numerous strong spiniform setae along ventral margin; carpus, merus and ischium with serrated ventral margin. Fourth pereiopod (Figs. 4 H, 5 I) similar to third pereiopod. Fifth pereiopod (Figs. 4 I, 5 J) with dactylus similar to third and fourth; propodus with four distolateral spiniform setae; carpus, merus and ischium unarmed. Uropod (Fig. 5 D) overreaching distal end of telson; exopod slightly longer than endopod, outer margin dentate, with two small spiniform setae and single longer one at distolateral margin (Figs. 3 H, 5 D). Variation. The Taiwanese specimen differs from all the other material in that the shape of the minor second chelae is dissimilar compared to the major one (Fig. 6 C, D); the fingers are relatively long, about 0.87 of palm length (versus 0.4 – 0.6) and lacking a well-developed molar and fossa process. The first pereiopods of the Taiwanese specimen are also relatively long and slender (compare Figs. 4 E and 5 F); carpus being about 16 times longer than maximum width (vs. 9.5 – 10.5) and the fingers being about 0.34 of palm length (vs. about 0.4). In contrast, the ambulatory pereiopods are similar and subequal in shape (compare Figs. 4 F-I and 5 G-J). As such this specimen corresponds to the diagnosis of P. uropodialis in Barnard (1958) and the illustration of that taxon in Marin and Caley (2011). Color. Whole body and appendages almost transparent with a pale reddish cream color, tiny red chromatophores scattered irregularly (Fig. 2).