Cancricepon castroi, An & Wang & Boyko & Williams, 2019

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 : 140-142

Cancricepon castroi n. sp.

( Figs 2 , 3 )

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Material examined. Infesting female Trapezia septata Dana, 1852 (11 mm CW, 9 mm CL) (UF 22339); mature dextral holotype female (4.5 mm), mature allotype male (1.3 mm, prepared for SEM) (UF 42206), Australia, Western Australia, Ningaloo Reef, Wreck Zirv, reef front, 22°36’30”S, 113°37’30”E, in Pocillopora sp., 10 m, May 2009, coll. J. Cale, L. Plaisance.

Infesting female Trapezia lutea Castro, 1997 (8.4 mm CW, 5.9 mm CL) (UF 39611); mature sinistral paratype female (3.7 mm), mature paratype male (1.6 mm) (UF 42207), Maldives, 0.3 km south of Magoodhoo Island, 10– 30 m forereef, in Pocillopora sp., 03°04’29”N, 72°57’59”E, 10 May 2014, coll. J. Moore.

Infesting male T. lutea (15.7 mm CW, 12.3 mm CL) (UF 27019); mature sinistral paratype female (7.2 mm), mature paratype male (1.9 mm) (UF 42208), Japan, Okinawa Prefecture, Okinawa Island, White Beach, 1–14 m, 26°17’44”N, 127°54’22”E, 17 July 2010, coll. N. Evans, F. Michonneau, G. Paulay, T. Naruse, Y. Ise.

Infesting male Quadrella coronata Dana, 1852 (6.9 mm CW, 5.4 mm CL) (UF 4821); juvenile non-type female (3.2 mm), 2 non-type cryptoniscus larvae (1.4 mm each) (UF 42209), Papua New Guinea, 02°22’06”S, 146°17’19”E, 29 June 2003, coll. L. Kirkendale.

Description. Female length 3.7 mm excluding uropods; maximum width (across pereomere 3) 3.7 mm; head length 1.1 mm, width 1.2 mm; length of uropods 1.1 mm (measurements based on holotype). All segments distinct; no pigmentation ( Fig. 2A, B ).

Head ovate, frontal lamina prominent, extending beyond both sides of head and frontal margin, notched medially ( Fig. 2A, B ); eyes lacking. Antennules and antennae of three and five articles each, respectively, terminally setose; all articles with scales ( Fig. 2C ). Barbula with 2 falcate pointed lateral projections on each side, outer projections larger than inner; median region with a pair of blunt triangular projections ( Fig. 2D ). Maxilliped with rounded anterior segment and large tapered palp, inner margin fringed with setae, plectron triangular, short and blunt ( Fig. 2E ).

Pereon broadest across pereomere 3 ( Fig 2A, B ). Coxal plates developed in first 4 pereomeres. Large tergal projections present on pereomeres 2–4, with projections on longer side of body larger than those on shorter side. Last three pereomeres with pointed mid-dorsal projections ( Fig 2A, B ). Brood pouch completely covered by oostegites, highly vaulted. Oostegite 1 ( Fig. 2F, G ) with two segments subequal in length, anterior segment ovate; internal ridge notched near lateral margin, with small tubercle; posterior margin fringed with setae, round posterolateral point extended laterally. Pereopods 1 ( Fig. 2H ) and 5–7 all small, with blunt dactyli, pereopods 2–4 large, with sharp dactyli ( Fig. 2I ). All pereopods with stout bases.

Pleon of six segments, first five pleomeres with 5 pairs of biramous pleopods and uniramous lateral plates. All pleopods and lateral plates with digitate margins, surfaces covered with tubercles ( Fig. 2J ). Uropods uniramous, similar to pleopods ( Fig. 2A, B, J ).

Allotype male length 1.8 mm; maximum width (across pereomeres 4–6) approximately 0.7 mm; head broader than long, length 0.2 mm, width 0.3 mm. All body regions and segments distinct ( Fig. 3A, B ).

Head elliptical, with rounded anterior margin; small, dark eyes near posterolateral corners ( Fig 3A ). Antennules with three articles each, distal margin of all articles with setae ( Fig. 3C ). Antennae with five articles each, second through fourth articles with single seta, distal segment with many setae ( Fig. 3C ).

Pereon with seven segments. Pereomeres 4–6 subequal in width, small patches of pigmentation present on some pereomeres and first pleomere ( Fig. 3A ). All pereomeres with rounded mid-ventral tubercles ( Fig. 3B ). First three pereopods larger than posterior four; dactyli of first three pereopods much larger than others ( Fig. 3 D–F), propodi, carpi and meri with ridged pad-like scales and tufts of setae on ventral surfaces ( Fig. 3 D–F).

Pleon with six pleomeres, lateral margins rounded ( Fig. 3A, B ). First five pleomeres with uniramous lateral digitiform pleopods, tips tapered, acute with terminal seta ( Fig. 3G ), first pleomere with midventral tubercle ( Fig. 3B ). Sixth pleomere (pleotelson) without uropods or posterolateral lobes, anal cone visible in ventral view ( Fig. 3B ).

Etymology. This species is named after Dr. Peter Castro (Professor Emeritus, California State Polytechnic University, Pomona) in honor of his contributions to trapeziid taxonomy.

Remarks. This new species can be distinguished from its closest relative, C. savignyi , by several characters of the female: all pereomeres with asymmetrical dorsolateral bosses (at least those on pereomere 2 symmetrical in C. savignyi ), maxilliped palp elongate and tapered (maxilliped palp stout and rounded at tip in C. savignyi ), endopods of pleopods less than 1/3 as large as exopods (endopods of pleopods 1/3 to 1/2 as long as exopods in C. savignyi ). Additional differences between C. castroi n. sp. and other species of Cancricepon are given in the key to species below. Differences between the males of the two species are difficult to determine, as the sole male described by Stebbing (1910) had unusual pleopod structures and may not have been fully mature.

No bopyrids were previously known from either Trapezia septata or T. lutea . No species of Quadrella Dana, 1851 , has ever previously been reported to bear bopyrids, although Q. coronata is the type host for Sacculina pilosella Van Kampen & Boschma, 1925 ( Cirripedia : Rhizocephala ) ( Van Kampen & Boschma 1925). Australia, the Maldives, and Papua New Guinea are new localities for species of Cancricepon .

Figures

FIGURE 2. Cancricepon castroi n. sp., holotype female (UF 42206) (A, D–J); paratype female (UF 42207) (B, C): A, B, dorsal view; C, right antennule and antenna; D, barbula, right side; E, left maxilliped, external view; F, left oostegite 1, external view; G, left oostegite 1, internal view; H, right pereopod 1; I, left pereopod 4; J, ventral view of terminal pereomeres and pleon, left side. Scale bars: A = 1 mm; B = 500 µm; C = 50 µm; D-G = 320 µm; H, I = 170 µm; J = 250 µm.

FIGURE 3. Cancricepon castroi n. sp., paratype male (UF 42207) (A–D, F, G); allotype male (UF 42206) (E): A, dorsal view; B, ventral view; C, left antennule and antenna; D, right pereopod 1; E, left pereopods 2 & 3; F, right pereopod 7; G, right pleopod 4. Scale bars: A = 200 µm; B = 250 µm; C, D, F, G = 50 µm; E = 10 µm.