Cancricepon cf. multituberosum An, Yu & Williams, 2012

An, Jianmei, Wang, Mingxiao, Boyko, Christopher B. & Williams, Jason D., 2019, New hosts and localities for species of Cancricepon Giard & Bonnier, 1887 (Isopoda: Epicaridea: Bopyridae) with description of two new species and comments on the relationship between Cancricepon and Trapezicepon Bonnier, 1900, Zootaxa 4559 (1), pp. 136-150 : 142-144

Cancricepon cf. multituberosum An, Yu & Williams, 2012

( Fig. 4 )

Material examined. Infesting Leptodius affinis (De Haan, 1835) (8.6 mm CW, 5.7 mm CL) (UF 29451); mature dextral female (damaged, ca. 3.0 mm excluding pleon), mature male (prepared for SEM, 0.95 mm) (UF 42216), Taiwan, Keelung area, near bridge to Chao-Jing Station, 0-2 ft (= 0–0.6 m) intertidal, 25°08’31”N, 121°48’11”E, 2 July 2011, coll. M. Bemis, M. Malay, J. Huang.

Description. Female total length 4.1 mm (including pleon and uropods), maximal width 2.5 mm across third pereomere, head length 0.8 mm (including frontal lamina), head width 1.0 mm. All body regions and segments distinct. No pigmentation ( Fig. 4A, B ).

Head subovate, wider than long, anterior margin slightly bilobate and posterior margin convex; large frontal lamina extending beyond both sides of head, anterior margin with two small notches; eyes absent ( Fig. 4A ). Antennules of three articles each, with stout basis and second article, distal article minute; antennae smaller than antennules, also of three articles each, all small; antennules and antennae with setae on distal two articles, all articles with scales ( Fig. 4C ). Barbula with two falcate projections on each side, outer projections larger than inner ones and highly curved; pair of triangular projections medially ( Fig. 4D ). Maxilliped with two segments, anterior segment much larger than posterior one ( Fig. 4E ); large and curving palp with terminal setae ( Fig. 4F ).

Pereon with distinct segments, broadest across pereomere 3 ( Fig 4A ); all pereomeres except first with middorsal projections, but pereomeres 2–4 with small round projections, pereomeres 5–7 with posteriorly pointed projections ( Fig. 4A, J ). First four pereomeres with rounded dorsolateral bosses and weakly developed tergal projections ( Fig. 4A, I ). Brood pouch completely covered by oostegites ( Fig. 4B ). First oostegite ( Fig. 4G, H ) with two subequally long articles, posterior article with irregular margin, internal ridge almost smooth, bearing a few small low projections near outer margin. Fifth oostegite with terminal setae and rounded tubercles on surface, covered with scales ( Fig. 4L ). Pereopods subequal in structure, large knob-like structure on each ischium; posterior pereopods larger ( Fig. 4I, K, L )

Pleon of six distinct pleomeres, first five with long lateral plates and biramous pleopods; lateral plates and pleopods with digitate margins, surfaces with small tubercules ( Fig. 4 L–P); endopodites less than half as large as associated exopodites. Sixth pleomere with uniramous uropods, margins digitate, longer than pleopod 5 ( Fig. 4Q ).

Male length 0.95 mm, maximal width across fourth pereomere 0.3 mm, head length 0.1 mm, head width 0.16 mm ( Fig. 4R ).

Head elliptical, anterior margin rounded, posterior margin truncate ( Fig. 4R ); conspicuous dark eyes near posterolateral margin ( Fig. 4R ). Head and first pereomere separated ( Fig. 4R ). Antennules with two articles each, first article with two setae, second article with 6–8 setae. Antennae with three articles each, first two articles with one seta, third article with 8 setae.

Pereon with pigment on pereomeres 2–7 and pleomeres 1–2 ( Fig. 4R ). All pereopods subequal in structure, first four pereopods larger than last three pairs. Carpi and meri of pereopods with one seta on ventral surface, propodi produced into plates covered in scales for receiving tips of dactyli. All pereomeres with midventral tubercles.

Pleon of six segments, first pleomere with midventral tubercle ( Fig. 4S ). First five pleomeres with low, rounded pleopods ( Fig. 4S ), sixth pleomere weakly produced into two rami, each terminated with tuft of setae ( Fig. 4S ), anal cone present medially ( Fig. 4S ).

Remarks. An et al. (2012) described C. multituberosum as having all pereomeres with middorsal triangular projections; the female from Leptodius affinis lacks a middorsal projection on the first pereomere. The present female specimen also differs from C. multituberosum in having a maxilliped with palp, whereas the maxilliped of C. multituberosum lacks a palp. The male of C. multituberosum has midventral tubercles on the first two pleomeres, whereas the present male has one only on the first pleomere. In all other aspects the present material agrees with C. multituberosum and, in the absence of more material from this host, we tentatively assign them to C. multituberosum . Leptodius affinis , has not previously been reported as a host for bopyrids.

Figures

FIGURE 4. Cancricepon cf. multituberosum An, Yu & Williams, 2012, female (UF 42216) (A–Q), male (UF 42216) (R, S): A, dorsal view; B, ventral view; C, left antennule and antenna; D, right side of barbula; E, right maxilliped, external view; F, palp of maxilliped; G, right oostegite 1, external view; H, right oostegite 1, internal view; I, left side of pereomeres 1–4 (ce = cephalon), dorsal view; J, lateral view of pereomeres 1–7 (ce = cephalon) showing middorsal projections; K, left pereopod 6; L, right pereopod 7, showing tubercles on surface of fifth oostegite and terminal setae; M, right pleopod 1; N, right pleopod 2; O, right pleopod 3; P, right pleopod 4; Q, right pleopod 5 and uropods; R, dorsal view; S, ventral view of pereomere 7 and pleon. Scale bars: A, B = 1 mm; C = 50 µm; K, L, S = 100 µm; D, E, G, H, M–Q = 500 µm; F = 110 µm; I, J = 500 µm; R = 250 µm.