Gigantione hainanensis, An & Yu & Markham, 2009

An, Jianmei, Yu, Haiyan & Markham, John C., 2009, First record of the genus Gigantione (Epicaridea: Bopyridae: Pseudioninae) from Chinese waters, with description of three new species, Journal of Natural History 43 (5 - 6), pp. 335-353 : 341-343

Gigantione hainanensis sp. nov.

( Figure 4 )

Material examined

Infesting Atergatis floridus (Linnaeus) . Dazhou Island, Sanya , Hainan, 18 ° 40 9 N, 110 ° 27 9 E, 11 June 1957, Coll. Yongliang Wang, 1♀, CIEX570601 , 1 „, CIEX570602 . Same locality, 27 March 1992, 1♀, CIEX920301 , 1 „, CIEX920302 . North Island, Xisha , 16 ° 54 9 N, 112 ° 18 9 E, 30 April 1957, Coll. Yongliang Wang, 1♀, CIEX570401 , 1 „, CIEX570402 . Xincun , Hainan, 19 ° 20 9 N, 110 ° 38 9 E, 9–13 July 1957, 1♀, CIEX570701 , 1 „, CiEX570702 .

Infesting Atergatis sp. Xizhou, Hainan, 18 ° 15 9 N, 109 ° 21 9 E, 3 April , 1962, 1♀, EX 620401, 1 „, CIEX620402 . Xincun , Hainan, 19 ° 20 9 N, 110 ° 38 9 E, 6 April 1962, 1♀, CIEX620403 , 1 „, CIE620404 .

Description of holotype (CIEX920301)

Length 10.54 mm, maximal width 12.19 mm across fourth pereomere, head length 2.77 mm, head width 3.31 mm. Body distorted about 25 ° sinistrally ( Figure 4A ).

Head pentagonal, with narrow frontal lamina in middle extending beyond both sides of head and produced into pair of anterolateral flaps. Eyes absent ( Figure 4A ). Antennae visible in dorsal view, of two and six articles respectively ( Figure 4B ). Barbula ( Figure 4C ) with one large falcate projection on each side, two pairs of small projections near middle region, and one pair of sharp projections in middle region. Maxilliped ( Figure 4D ) nearly trapezoid, palpless, its anterior article much larger than posterior one and marginally fringed by dense setae.

Pereon largely enclosing both head and pleon, broadest across fourth pereomere. All pereomeres with long and slender coxal plates tapering to tips, those on long sides longer posteriorly. Coxal plates more developed on longer side than opposite. Dorsolateral bosses on both sides of first four pereomeres. Brood pouch completely enclosed by oostegites. First oostegite ( Figure 4E,F ) with much larger anterior article, wide and deep groove separating it from posterior article externally; internal ridge bearing four long slender flexible projections. Posterior margin flat and lacking posterolateral point. First four pereopods on long side visible dorsally along side of body, others not visible in dorsal view, all about the same size, each with basis produced into prominent lobe along flexor margin ( Figure 4G,H ).

Pleon of six distinct pleomeres, first five produced into lateral plates on both sides; lateral plates on long side longer than those on short side, but lateral plates on short side wider than those on long side. Terminal pleomere without lateral plates, inside general outline of body. All pleopods biramous, visible only in posterior view. First pleopod lamellar, much larger than other pleopods, other four pairs of pleopods with deeply digitate margins, nearly triramous, including endopodites and exopodites with inner and outer lobes, ( Figure 4I–L ). Each biramous uropod with cylindrical basis, two rod-shaped branches.

Description of allotype male (CIEX920302)

Length 4.24 mm, maximal width, across fifth pereomere, 1.43 mm, head length 0.45 mm, pleonal length 1.67 mm. Body gradually tapering posteriorly, all segments distinct ( Figure 4M,N ).

Head semicircular, broader than long. Conspicuous dark eyes near posterior edge. Head and first pereomere distinctly separated ( Figure 4M ). Antennae of three and six articles respectively, second antennae extending beyond margins of head on both sides ( Figure 4O ).

Pereon broadest across fifth pereomere, first pereopod larger than other six pereopods, second to seventh pereopods equally developed and about same size, with all articles distinct ( Figure 4P,Q ).

Pleon of six segments, first five pleomeres with long rod-shaped, medially directed uniramous pleopods. Last segment semicircular, with column-shaped uniramous uropods.

Etymology

The specific name, the word hainanensis , in the form of a third declension Latin adjective, refers to the type locality of the types, Hainan Island, China.

Remarks

The present specimens appear to be most closely related to G. ishigakiensis Shiino, 1941 , which also infests xanthiid crabs. The new species differs from G. ishigakiensis in the shape of its barbula, the posterior edge of oostegite 1, and in having a subrectangular maxilliped. The female of G. ishigakiensis has a narrow frontal lamina, second antennae extending beyond the margin of the head, barbula with a pair of pointed projections on the middle region and a maxilliped with a projection on the palp region. The new species is distinguished from G. ishigakiensis by the absence of a frontal lamina, antennae not visible in dorsal view, a pair of blunt projections on the middle region of barbula, and the maxilliped without any projection in the palp region.

Distribution and hosts

Hainan, China, infesting Atergatis floridus (Linnaeus) and Atergatis sp.

Figures

Figure 4. Gigantione hainanensis sp. nov. Holotype female: (A) dorsal view; (B) left antennae; (C) barbula; (D) left maxilliped, external view; (E) right oostegite 1, external view; (F) right oostegite 1, internal view; (G) right pereopod 1; (H) right pereopod 7; (I) right pleopod 1; (J) right pleopod 3; (K) right pleopod 4; (L) right pleopod 5. Allotype male: (M) dorsal view; (N) ventral view; (O) left antennae; (P) pereopod 1; (Q) pereopod 4. Scale bar: 1 mm (A); 0.17 mm (B,G,H); 0.15 mm (O–Q); 0.42 mm (C,M,N); 0.50 mm (D); 0.83 mm (E,F); 0.71 mm (I–L).