Eophrixus caudatus, An & Boyko & Li, 2015

An, Jianmei, Boyko, Christopher B. & Li, Xinzheng, 2015, A Review Of Bopyrids (Crustacea: Isopoda: Bopyridae) Parasitic On Caridean Shrimps (Crustacea: Decapoda: Caridea) From China, Bulletin of the American Museum of Natural History 2015 (399), pp. 1-85 : 67-70

Eophrixus caudatus , n. sp.

Figures 20 , 21A, B

Eophrixus shojii An, 2006: 172–173 , fig. 88 (not Eophrixus shojii Shiino, 1941 ).

MATERIAL EXAMINED: Infesting Alpheus microstylus ( Bate, 1888) (fig. 17A, B), holotype ♀ ( CIEAL 800501), allotype ♂ ( CIEAL 800502): Xisha Coral Island, 16 ° 32′ N, 111 ° 36′E, 9–21 May 1980.

DESCRIPTION: Holotype female ( CIEAL 800501 ): Length 6.11 mm, including lateral plates, maximal width 4.43 mm, including brood pouch, head length 0.56 mm, head width 1.56 mm (figs. 20A, 21A, B).

Body strongly asymmetrical, with swollen pereon. Head inserted into pereon, with bilobate anterior and posterior margins, without eyes (fig. 20A). Antennule of three articles, antenna of four articles, both setose, with stout bases (fig. 20C). Maxilliped rectangular, without palp, plectron blunt, anterior article 3 times larger than posterior article (fig. 20D). Barbula with two pairs of simple falcate lateral projections on each side (fig. 20E).

Left side of body somewhat fused, but right side distinctly segmented with pereopods closely crowded together. Dorsolateral bosses and coxal plates absent. Swollen brood pouch completely closed (fig. 20A). Oostegite 1 (fig. 20F, G) with smooth internal ridge, posterolateral point rounded and directed laterally. Seven pereopods crowded together on short side, but first two pereopods on long side near head, third pereopod inserted in brood pouch, last four pereopods crowded between brood pouch and lateral plates. All pereopods slender, with long meri, dactyli longer in posterior pereopods (fig. 20H, I). Pleon with four pairs of lateral plates and biramous pleopods, segmentation indistinct. All lateral plates and exopodites of pleopods lobate, endopodites well developed (fig. 20B). Terminal pleomere with distinct uniramous uropods (fig. 20B).

DESCRIPTION: Allotype male (CIEAL8 00502): Length 3.53 mm, maximal width (across pleon 4) 0.93 mm, head width 0.67 mm, head length 0.33 mm (fig. 20J, K). Head semicircular (fig. 20J), fused with first pereomere; small black eyes posterolaterally (fig. 20J). Antennule of three articles, almost smooth, antenna of six articles, terminal two articles setose (fig. 20L). All pereomeres subequal in width, lacking midventral projections (fig. 20K). All pereopods of same size and structure, carpi and meri terminally setose, dactyli blunt (fig. 20N). Pleon fused into single piece, without any pleopods; lateral margins straight, without any notches or incisions. Posterior margin of pleon with pair of fingerlike uropodal rami, anal cone in median (fig. 20M).

ETYMOLOGY: The specific name, caudatus , refers to the female bearing a pair of distinct, forked, fingerlike uropods.

HOST AND LOCALITY: Infesting Alpheus microstylus ( Bate, 1888) (Alpheidae) , Xisha (Paracel Islands), China.

REMARKS: The female of the new species has a swollen brood pouch, seven pairs of pereopods on both sides, and the male has a fused pleon, indicating that the present specimens belong to Eophrixus . The new species can be distinguished from the other 10 well-described species by its unique forked fingerlike uropods. Eophrixus caudatus , n. sp., is most closely related to E. shojii Shiino, 1941 , but the new species differs from E. shojii as follows: (1) the first lateral plates of the new species are almost equal in size to the others, whereas the first lateral plates of E. shojii are much smaller than the others; (2) the female of the new species has prominent forked uropods while the uropods of E. shojii are small and globular; (3) the male of the new species lacks any indentation or notch on the pleon margin, but the male of E. shojii shows a distinct series of indentations indicating the pleomeres.

Figures

Fig. 20. Eophrixus caudatus, n. sp., holotype female (CIEAL800501) (A–G): A. Dorsal view. B. Ventral view of pleon. C. Left antenna and antennule. D. Left maxilliped. E. Barbula of right side. F. Right oostegite 1, external view. G. Right oostegite 1, internal view. H. Left pereopod 5. I. Left pereopod 6. Allotype male (CIEAL800502) (J–N): J. Dorsal view. K. Ventral view. L. Right antenna and antennule. M. Ventral view of pleon. N. Right pereopod 7. Scale: 1 mm (A); 0.6 mm (B, E–G, J, K); 0.45 mm (D); 0.2 mm (C, N); 0.15 mm (H, I, L, M).

Fig. 21. Hemiarthrine bopyrids and hosts. A. Host of Eophrixus caudatus, n. sp. B. Female, male and eggs of E. caudatus. C. Host of Sigyn branchialis, n. gen., n. sp. (right branchial chamber bulge indicating bopyrid, arrows indicating rhizocephalans). D. Dorsal view of female of S. branchialis, n. gen., n. sp. with attached male.