Parapenaeon calculosa sp. nov.

(Figure 6)

Material examined

Infesting Trachysalambria curvirostris (Stimpson) . Holotype, CIEPE403901-1, ♀, allotype, CIEPE403901-2, ♂, East China Sea, Stn. 4039, 31°30 ′ N, 124°00 ′ E, 44.5 m, 25 October 1959, coll. Liren Chen. Paratype, CIEPE403801, ♀, ♂, East China Sea, Stn. 4038, 31°30 ′ N, 123°30 ′ E, 41 m, 8–9 December 1959, coll. Zhican Tang. Other materials: CIEPE405101, ♀, immature, East China Sea, Stn. 4051, 30° 00 ′ N, 124°00 ′ E, 57 m, 7 December 1959, coll. Yongliang Wang and Jinzhao Zhu. CIEPE404602, ♀, ♂, East China Sea, Stn. 4046, 30°30 ′ N, 123°30 ′ E, 57 m, 7 December 1959. coll. Yongliang Wang. CIEPE404202, ♀, ♂, East China Sea, Stn. 4042, 31°00 ′ N, 123°30 ′ E, 50.5 m, 10 December 1959, coll. Guangyu Lin and Minshou Li. CIEPE401201, ♀, ♂, East China Sea, Stn. 4012, 33°30 ′ N, 124°00 ′ E, 72 m, 6 April 1959, coll. Jinzhou Zhu. CIEPE400801, ♀, East China Sea, Stn. 4008, 33°30 ′ N, 123°00 ′ E, 46 m, 6 December 1959, coll. Jieshan Xu. CIEPE403501, ♀, ♂, East China Sea, Stn. 4035, 32°00 ′ N, 124°00 ′ E, 42.8 m, 24 October 1959, coll. Liren Chen. CIEPE403502, ♀, ♂, East China Sea, Stn. 4035, 32°00 ′ N, 124°00 ′ E, 42.8 m, 24 October 1959, coll. FuZeng Sun. CIEPE403301, 2♀♀, 2♂♂, East China Sea, Stn. 4033, 32°00 ′ N, 123°00 ′ E, 36.8 m, 24 October 1959, coll. Liren Chen. CIEPE403401, ♀, ♂, East China Sea, Stn. 4034, 32°00 ′ N, 123°30 ′ E, 44 m, 24 October 1959, coll. Liren Chen. CIEPE403302, ♀, East China Sea, Stn. 4033, 32°00 ′ N, 123°00 ′ E, 35 m, 9 July 1959, coll. Xuan Zhang. CIEPE403402, ♀, ♂, East China Sea, Stn. 4034, 32° 00 ′ N, 123°30 ′ E, 44 m, 24 October 1959, coll. Liren Chen. CIEPE601201, ♀, ♂, Guangdong Province, Stn. 6012, 22°30 ′ N, 117°00 ′ E, 47.3 m, 31 December 1959 . CIEPE403403, ♀, ♂, East China Sea, Stn. 4034, 32°00 ′ N, 123°30 ′ E, 44 m, 24 October 1959, coll. Liren Chen. CIEPE404701, ♀, ♂, East China Sea, Stn. 4047, 30°30 ′ N, 124°00 ′ E, 53 m, 3 February 1959, coll. Yuhang Cui. CIEPE400701, ♀, immature, East China Sea, Stn. 4007, 33°30 ′ N, 122°30 ′ E, 39 m, 24 October 1959, coll. Liren Chen. CIEPE550503, 8♀♀, 6♂♂, Yingge Sea Fish Market, 18°30 ′ N, 108° 45 ′ E, 7 May, 1955, coll. Yongliang Wang. CIEPE404203, 2♀♀, 2♂♂, East China Sea, Stn. 4042, 31°00 ′ N, 123°30 ′ E, 57 m, 2 February 1959, coll. Liren Chen. CIEPE403902, 2♀♀, 2♂♂, East China Sea, Stn. 4039, 31°30 ′ N, 124°00 ′ E, 44.5 m, 25 October 1959, coll. Liren Chen. CIEPE403404, 2♀♀, 2♂♂, East China Sea, Stn. 4034, 32°00 ′ N, 123°30 ′ E, 44 m, 24 October 1959, coll. Liren Chen. CIEPE404204, ♀, ♂, East China Sea, Stn. 4042, 31°00 ′ N, 123°30 ′ E, 50.5 m, 10 December 1959, coll. Guangyu Lin and Minshou Li. CIEPE403903, 2♀♀, 2♂♂, East China Sea, Stn. 4039, 31°30 ′ N, 124°00 ′ E, 45 m, 7 July 1959, coll. Jinzhou Zhu. CIEPE404301, 2♀♀, 2♂♂, East China Sea, Stn. 4043, 31°00 ′ N, 124°00 ′ E, 44 m, 25 October 1959, coll. Liren Chen.

Description of holotype female (CIEPE403901-1) (Figure 6A–J)

Length 7.72 mm, maximal width 5.69 mm, head length 1.47 mm, head width 1.64 mm (Figure 6A, B).

Head oval, with well-developed frontal lamina. Eyes absent (Figure 6A). First antenna of three articles, second antenna of five articles, both non-setose. Maxilliped triangular, with curved stout palp (Figure 6C). Barbula with one digitate lateral projection on each side and single smooth projection near centre (Figure 6D). Pereon (Figure 6A) broadest across pereomere 3. Pereomeres 2–5 fused medially. Coxal plates well-developed on long side of each pereomere, margins of the first two coxal plates slightly dentate. Coxal plates well developed on short sides of first two pereomeres also, but others rudimentary. Round dorsolateral bosses on first five pereomeres. Brood pouch (Figure 6B) opens medially. First oostegite (Figure 6E, F) with both plates nearly equally long, internal ridge bearing many digitate projections, posterolateral point round, with straight posterior edge. Pereopods (Figure 6G, H) larger posteriorly, carpi and meri smooth, bases of all pereopods produced into lobes.

Pleon of six pleomeres, first five bearing lateral plates and biramous pleopods. Surface of first five lateral plates tuberculate. Pleopods and uropods similarly tubercular (Figure 6I). Sixth pleomeres without lateral plates, but with biramous uropods (Figure 6J).

Description of allotype male (CIEPE403901-2) (Figure 6K–O)

Length 2.21 mm, maximal width across pereonite 4, 1.04 mm, head width 0.55 mm, pleonal length 0.45 mm.

Head elliptical with curved posterior edge (Figure 6K). Eyes absent. First antenna of three articles, with setae on distal article; second antenna of five articles, terminal two or three articles setose (Figure 6M).

Pereomeres almost equally wide, lacking midventral projections (Figure 6L). All pereopods of similar size, first three pereopods with much larger dactyli and smaller carpi (Figure 6L).

Pleon fused and oval, without midventral projections, lacking pleopods and uropods (Figure 6K, L).

Variations

Paratype females differ little from the holotype. An immature female (CIEPE405101) has dentate coxal plates on first three pereomeres on long sides, those on short sides being smaller than those on long sides (Figure 6N, O). Slender pleopods extend beyond the lateral plates, and are visible in dorsal view.

Etymology

The specific name, calculosa a Latin adjective meaning ‘pebbly’, refers to the surfaces of the pleopods of the holotype female, which are thickly tuberculated in a pattern reminiscent of small stones or pebbles.

Remarks

The female of P. calculosa, as in other species of the genus Parapenaeon, has six pleomeres, the first five bearing lateral plates. The male has a pleon fused and lacking appendages, as is typical for Parapenaeon . The new species is most similar to P. japonica (Thielemann 1910) . The new species differs from P. japonica in the following. (1) The new species has a straight posterior edge of the first oostegite, but all specimens of P. japonica have curved posterior edge of the first oostegite. (2) Sixth pleomeres of the new species can be seen from dorsal view (Figure 6A, J), but in P. japonica only five pleomeres can be seen, sixth pleomere usually hidden under the fifth pleomere (Figures 1A, 2A, 3A). (3) The new species with tubercles on the surface of the lateral plates, and P. japonica with smooth lateral plates. (4) The new species barbula with one pairs of digitate projections, and the barbula of P. japonica with two pairs of digitate projections. (5) Male of the new species with smooth pleon, without anal cone or other tubercles, and P. japonica with distinct anal cone, some specimens with midventral tubercular on the pleon (Figure 3J).