Dactylokepon barbuladigitus, An & Yu & Williams, 2007

An, Jianmei, Yu, Haiyan & Williams, Jason D., 2007, Four new records and a new species of Dactylokepon Stebbing, 1910 (Epicaridea: Bopyridae: Ioninae) from Chinese waters, Journal of Natural History 41 (33 - 36), pp. 2063-2079 : 2073-2078

Dactylokepon barbuladigitus new species

( Figures 6 , 7 )

Material examined

Infesting Liagore rubromaculata (De Haan) . Holotype: South Sea , Stn 6045, 21 ° 459N, 114 ° 309E, 64.5 m, 9 April 1959, Guangzong Wu coll., 1♀, CIEX604501 . Allotype: South Sea , Stn 6045, 21 ° 459N, 114 ° 309E, 64.5 m, 9 April 1959, Guangzong Wu coll., 1 „, CIEX604502 . Paratypes: East Sea, Stn 4054, 29 ° 309N, 123 ° 309E, 69 m, 8 December 1959, Yongliang Wang coll., Zhu, 1♀, CIEX405401 , 1 „, CIEX405402 . South Sea , Stn 6045, 21 ° 459N, 114 ° 309E, 59.6 m, 8 April 1959, Jingzuo Qu coll., 2♀, CIEX604505 , 1 „, CIEX604506 .

Other materials. South Sea , Stn 6045, 21 ° 459N, 114 ° 309E, 64.5 m, 9 April 1959, Guangzong Wu coll., 1♀, CIEX604509 , 1 „, CIEX604510 . South Sea , Stn 6045, 21 ° 459N, 114 ° 309E, 59.6 m, 8 April 1960, Jingzuo Qu coll., 1♀, CIEX604511 , 1 „, CIEX604512 . South Sea , Stn 6090, 21 ° 009N, 112 ° 309E, 53 m, 22 October 1959, Yongliang Wang coll., 3♀, CIEX609001 , 2 „, CIEX609002 . South Sea , Stn 6090, 21 ° 009N, 112 ° 309E, 52 m, 6 July 1959, coll., 3♀, CIEX609003 , 3 „, CIEX609004 . South Sea , Stn 6132, 19 ° 459N, 111 ° 159E, 66 m, 12 July 1959, Zhican Tang coll., 2♀, CIEX613201 , 2 „, CIEX613202 . South Sea , Stn 6131, 20 ° 009N, 111 ° 159E, 52 m, 25 April 1959, Xiutong Ma coll., 4♀, CIEX613101 , 4 „, CIEX613102 . South Sea , Stn 6131, 20 ° 009N, 111 ° 159E, 48 m, 12 July 1959, Zhican Tang coll., 1♀, CIEX613105 , 1 „, CIEX613106 . South Sea , Stn 6131, 20 ° 009N, 111 ° 159E, 44 m, 29 October 1959, Mingshou Li coll., 1♀, CIEX613107 , 1 „, CIEX613108 . South Sea , Stn 6106, 20 ° 309N, 112 ° 009E, 65 m, 29 October 1959, Yongliang Wang coll., 1♀, CIEX610603 , 1 „, CIEX610604 . South Sea , Stn 6119, 20 ° 159N, 111 ° 309E, 70 m, 12 April 1959, Xiutong Ma coll., 2♀, CIEX611903 , 2 „, CIEX611904 . South Sea , Stn 6118, 20 ° 309N, 111 ° 309E, 61 m, 16 July 1959, Zhican Tang coll., 3♀, CIEX611801 , 2 „, CIEX611802 . South Sea , Stn 6035, 22 ° 009N, 115 ° 009E, 63 m, 21 March 1959, Weiquan Zhang coll., 1♀, CIEX603501 , 1 „, CIEX603502 . South Sea , Stn 6105, 21 ° 009N, 112 ° 009E, 45 m, 4 April 1960, Zhican Tang coll., 1♀, CIEX610501 , 1 „, CIEX610502 . South Sea , Stn 6105, 21 ° 009N, 112 ° 009E, 45 m, 5 February 1960, Jingzuo Qu coll., 2♀, CIEX610503 , 1 „, CIEX610504 . South Sea , Stn 6117, 20 ° 459N, 111 ° 309E, 49 m, 17 July 1959, Zhican Tang coll., 1♀, CIEX611701 , 1 „, CIEX611702 . South Sea , Stn 6168, 18 ° 309N, 110 ° 159E, 46 m, 4 April 1959, Zhengang Fan coll., 1♀, CIEX616801 , 1 „, CIEX616802 . South Sea , Stn 6142, 19 ° 009N, 111 ° 009E, 96 m, 8 April 1960, Yongliang Wang coll., 1♀, CIEX614201 , 1 „, CIEX614202 . South Sea , Stn 6075, 21 ° 309N, 113 ° 009E, 36 m, 6 July 1959, Xiutong Ma coll., 1♀, CIEX607501 , 1 „, CIEX607502 . South Sea , Stn 6044, 22 ° 009N, 114 ° 309E, 43.6 m, 9 April 1959, Jingzuo Qu coll., 1♀, CIEX604401 , 1 „, CIEX604402 . East Sea , Stn 105, 26 ° 309N, 122 ° 009E, 85 m, 12 June 1978, Zhican Tang and Jieshan Xu coll., 1♀, CIEX10501 , 1 „, CIEX10502 . South Sea , Stn 6116, 21 ° 009N, 111 ° 309E, 41 m, 6 February 1960, Guangzong Wu coll., 1♀, CIEX611601 . South Sea , Stn 6119, 20 ° 159N, 111 ° 309E, 71.5 m, 18 October 1959, Zhican Tang coll., 1♀, CIEX611901 , 1 „, CIEX611902 . South Sea , Stn 6047, 21 ° 159N, 114 ° 309E, 82 m, 10 July 1959, Jingzuo Qu coll., 1♀, CIEX604701 , 1 „, CIEX604702 .

Description of holotype (CIEX604501)

Length (excluding uropods) 7.11 mm, maximal width 5.2 mm, head length 1.87 mm (including frontal lamina), head width 2.34 mm, pleon length 1.21 mm, distortion 32 °. All body regions and segments distinct. No pigmentation ( Figure 6A ).

Head widely bilobate, wider than long, posterior margin broadly v-shaped, bearing welldeveloped, trifid, frontal lamina with wide medial lobe, and two lobes on sides of head. Eyes absent ( Figure 6A ). Antenna of five articles, antennule of three articles: few setae except for with three terminal setae on antenna ( Figure 6C ). Maxilliped with large, falcate non-articled, non-setose palp and blunt plectron ( Figure 6D ). Barbula with two prominent digitate lateral projections on each side, flat middle region, outer projection distinctly longer than inner ones ( Figure 6E ).

Pereon broadest across third pereomere, gradually tapering on each side posteriorly. Coxal plates absent. No middorsal projections on pereon. Dorsolateral bosses on first four pereomeres, with small tubercles on concave margin of third and fourth pereomeres. Prominent tergal projections on second to fourth pereomeres, with a row of small tubercles on left side of tergal projections ( Figure 6A ). Oostegites completely enclosing highly vaulted brood pouch ( Figure 6B ). First oostegite ( Figure 6F, G ) smoothly rounded anteriorly, with digitate internal ridge and prominent digitate projection, round posterolateral point with long irregular setae. Second to fourth oostegite with setate posterior margins, anterior margins smooth, third oostegite largest. Pereopods similar, propodi, carpi and meri setate, but first two pereopods ( Figure 6H ) with stout carinate propodi. Third to fourth pereopods essentially alike except progressively longer posteriorly, basis and propodi slender ( Figure 6I ).

Pleon of six pleomeres, first five bearing biramous pleopods and lateral plates, all digitate, posterior sides with longer projections than anterior ones. Lateral plates of first three pleomeres slightly longer than respective exopodites, lateral plates of fourth and fifth pleomeres shorter than their exopodites ( Figure 6J–L ). Endopodite of fourth pleopod longer than its exopodite and the rest slightly shorter than their exopodites ( Figure 6K ). Uniramous uropods similar to structure of pleopods and lateral plates.

Description of allotype (CIEX604502)

Length 4.18 mm, maximal width across pleon 4, 1.11 mm, head length 0.46 mm, head width 0.82 mm, pleonal length 1.61 mm.

All body segments distinct, small patches of pigment on dorsal surface of third to fifth pereomeres ( Figure 6M ). Outline of body smoothly tapering posteriorly from fifth pereomere.

Head semicircular, small eyes in posterolateral regions ( Figure 6M ). Antenna of five articles, with setae on distal three articles; antennule of three articles, with two or three setae at distal extremity of two basal articles and tuft at tip of terminal article ( Figure 7B ).

Second to fifth pereomeres almost equally wide, with pointed margins. All pereomeres with prominent midventral projections ( Figure 7A ). First and second pereopods larger than other five pereopods, dactyli and propodi much larger on first two pereopods than third to fifth pereopods ( Figure 7D ).

Pleon of six pleomeres, first five with flap-like pleopods, without midventral projections ( Figure 7A ), sixth pleomere produced into two rounded symmetrically extending posterior lobes (true uropods lacking), each lobe bears setae on distal margin ( Figure 7E ); small anal cone extending posteriorly between lobes ( Figure 7D ).

Etymology

The specific name barbuladigitus refers to its distinct digitate barbula of holotype female.

Variation

Paratype females agree in all respects with the holotype, except that one paratype has a frontal lamina as wide as the head and does not extend beyond the head, as in the holotype, and the first pereomere is bisected by the head dorsally (CIEL626401). Two paratype males differ from the allotype in having asymmetrical projections on the sixth pleomere. Another paratype male has a prominent anal cone which is longer than the lobes of the sixth pleomere.

Remarks

With the addition of the new species, there are 11 species in the genus Dactylokepon . The new species, D. barbuladigitus , is distinguished from the other 10 species by the prominent trifid frontal lamina and distinct digitate barbula. Dactylokepon barbuladigitus appears to be most closely related to D. semipennatus and D. richardsonae , which are known to infest xanthid crabs. The new species differs from D. semipennatus in its distinct barbula, trifid frontal lamina, and curved maxilliped palp. Females of D. semipennatus have a barbula with slightly digitate projections, smooth round frontal lamina without any indentations, and a short palp on the maxilliped. The new species is distinguished from D. richardsonae by the posterolateral point of the first oostegite, shape of the frontal lamina and head, segmentation of antennae, and barbula. In D. richardsonae , the first oostegite has a sharp posterolateral point, slightly digitate barbula, a round frontal lamina and oval head, and antenna and antennule of four and two articles, respectively. Males of D. barbuladigitus differ from males of D. richardsonae in the distinctly separated head and the shape of the final pleomere. Finally, males of D. barbuladigitus can also be distinguished from D. caribaeus , D. hunterae Wells and Wells, 1966 by the distinct midvental projections on the pereomeres.

Many host specimens of D. barbuladigitus have both branchial chambers infested, and one chamber hosts D. barbuladigitus , while the other chamber hosts Gigantion e n. sp. (to be described in a later paper). Although many bopyrids infested both branchial chambers of their hosts, it is the first time that two different species were found in the two chambers of one and the same host.

Distribution and hosts

South Sea, China, on Liagore rubromaculata (De Haan) .

Figures

Figure 6. Dactylokepon barbuladigitus new species. (A–K) Holotype female: (A) dorsal view; (B) ventral view; (C) left antennae; (D) right maxilliped, external view; (E) barbula (right side); (F) right oostegite 1, external view; (G) right oostegite 1, internal view; (H) left pereopod 2; (I) right pleopod 3; (J) right pleopod 4; (K) right pleopod 5. (L) Allotype male (no.CIEX604502), dorsal view. Scale bar: 1 mm (A, B); 0.18 mm (C); 0.31 mm (D, E); 0.45 mm (F, G); 0.15 mm (H); 0.26 mm (I); 0.69 mm (J–L); 0.39 mm (M).

Figure 7. Dactylokepon barbuladigitus, new species, allotype, SEM micrographs. (A) Ventral view; (B) right antennae; (C) pereopods 1–3, left side; (D) ventral view of pleomere 6, showing small anal cone extending posteriorly between two lobes; (E) distal margin of lobe of pleomere 6. Scale bars: 1 mm (A); 100 mm (B–D); 10 mm (E).