Pagurion tuberculata Shiino, 1933

An, Jianmei, Li, Xinzheng & Markham, John C., 2013, Three Isopod Parasites (Bopyridae: Pseudioninae), Including Two New Species, Of Hermit Crabs From The South China Sea, Raffles Bulletin of Zoology 61 (2), pp. 561-569 : 561-564

Pagurion tuberculata Shiino, 1933

( Fig. 1 )

Pagurion tuberculata Shiino, 1933: 254–256 ; fig. 2 [type locality: Tanabe Bay, Japan; infesting Pagurus watasei Terao, 1913 (= Dardanus scutellatus H. Milne Edwards, 1848 )]. Shiino, 1972: 7. Harada, 1991: 201. Saito et al., 2000: 36. Markham, 2003: 72. Madad, 2008: 2, 5, 6, 17, 33–34, 48, 51, 86, 87; fig. 9 [Batangas, Philippines; infesting Clibanarius gaimardii (H. Milne Edwards, 1848) [= Calcinus gaimardii (H. Milne Edwards, 1848) ], Calcinus minutus Buitendijk, 1937 ] and Dardanus lagopodes ( Forsskål, 1775) ]. Markham, 2010: 151, 152; tab. 1, 156–158; figs. 6, 7 [Queensland, Australia; infesting Dardanus arrosor (Herbst, 1796) ]. McDermott et al., 2010: 8; tab. 1.

Material examined. — Infesting Dardanus aspersus ( Berthold, 1846) , 1♀, CIEA600401 , 1♂, CIEA600402 , South China Sea, Stn 6004, 23°30'N, 117°30'E, 39 m, coll. Huiliang Chen, 24 Apr.1960 .

Remarks. — Of the five specimens of Dardanus aspersus ( Berthold, 1846) examined, only one was infested with Pagurion tuberculata . This, the fourth record of P. tuberculata , is the first from China. The present specimens match the description of P. tuberculata by Shiino (1933) thus: 1) slight distortion of body; 2) non-extended smoothly rounded head bearing thin frontal lamina across all of anterior margin; 3) heavy tuberculation of oostegites and pleopods; 4) extensive setation of maxillipedal palp; 5) deeply digitate fringes on barbula and interior ridge of first oostegite; and 6) distinctive lateral coverage of final one or two pleomeres by preceding pleomeres. The present female differs from those of P. tuberculata recorded from Queensland, Australia, by Markham (2010) thus: eyes present, posterolateral point rounded, left first three and right first four pereomeres with prominent dorsolateral bosses ( Fig. 1A ). In contrast, the females from Australia lacked eyes, had sharp posterolateral points, and only the left and right first two pereomeres bearing dorsolateral bosses ( Markham, 2010). In both the present females and those from Australia, the maxillipedal palp ( Fig. 1D, E ) articulates fully. Shiino’s (1933) description of the type female did not mention the palp. In the present specimen, the first oostegite ends in a round posterolateral point ( Fig. 1G, H ), more similar to that of the type than to those from Australia.

All known male specimens, namely the present specimen, Australian specimens and Shiino’s type male, have short heads about half as broad as the first pereomeres, sides of pereon nearly parallel, dactyli of pereopods of the first two or three pairs ( Fig. 1 R–U) much larger than those of the following pereopods and five pairs of flaplike pleopods. In the present male and Shiino’s type male, the final two pleomeres are separated, in contrast with the partial fusion of the final two pleomeres of the Australian male. Madad (2008) presented the only SEM images prior to the present work showing that the male from the Philippines bore minute tubercles on articles of the pereopods. The shape of the pleopods of the present male is more similar to that of Madad’s (2008) Philippine specimen than other known specimens of the species.

All reported hosts of Pagurion tuberculata , including this record, belong to the Diogenidae , in the genera Dardanus and Calcinus . Although the geographic range of P. tuberculata seems extensive, it is evidently never common. The sample from Australia ( Markham, 2010) consisted of two pairs, while the present material and the other two known collections were all of single pairs. The previously known distribution and hosts of Pagurion tuberculata are summarised in the synonymy above. This is the first record of bopyrid infestation of Dardanus aspersus , a member of the genus most commonly recorded to host P. tuberculata elsewhere.

Pagurion arrosor , new species

( Fig. 2 )

Material examined. — Infesting Dardanus arrosor (Herbst, 1796) . South China Sea, Stn 6238, 20°00'N, 108°00'E, 83 m, Fengshan Xu, coll. 27 Feb.1958: 1 ♀, holotype, CIEA623801 ; 1 ♂, allotype, CIEA623802 .

Description of holotype female ( Fig. 2 A–K). — Length 13.01 mm, maximal width (across third pereomere) 10.16 mm, head length 2.42 mm, head width 3.39 mm, pleon length 3.27 mm, distortion 8°. All body regions and segments distinct. No pigmentation ( Fig. 2A, B ).

Head subelliptical, without frontal lamina, anterior edge with deep semicircular notch. Eyes absent. Antennae of 4 and 5 articles, respectively ( Fig. 2C ), without setae; basal articles of second antennae greatly expanded. Maxilliped ( Fig. 2D, E ) with prominent articulating palp bearing many setae on margin, some medial setae longer than others; anteromedial margin of maxilliped bearing shorter setae. Barbula ( Fig. 2F ) with one large digitate projection on each side, many small projections near middle region.

Pereomeres distinct, third one broadest; coxal plates on right sides of pereomeres 1–4 and left sides of pereomeres 1–5; slight medial depressions along anterior margins of pereomeres 3–7. Brood pouch completely enclosed by oostegites ( Fig. 2B ). Anterior segment of oostegite 1 ( Fig. 2G, H ) with anteriorly setose margin and patch of tubercules on external surface near lateral margin, internal ridge bearing many irregularly digitate projections, short bluntly rounded falcate posterolateral point with large swelling on inner surface. Pereopods all of about same size, dactyli reduced, bases with large round tubercules ( Fig. 2I )

Pleon of 6 pleomeres, first four produced into small lateral plates. Large foliate tuberculate biramous pleopods ( Fig. 2J, K ) on pleomeres 1–4 almost completely covering ventral surface of pleon. Pleomere 5 with slender triangular lateral plates and biramous pleopods. Short terminal (sixth) pleomere reflexed under fifth pleomere, without lateral plates. No uropods.

Description of allotype male ( Fig. 2 L–P). — Length 4.93 mm, maximal width (across pereomere 7) 1.79 mm, head length 0.80 mm, head width 0.90 mm, pleonal length 1.95 mm. All body segments except last two pleomeres distinct. Sides of body nearly parallel medially and smoothly tapered posteriorly. Minute black eyes, but no other pigment ( Fig. 2L, M ).

Head almost circular, bearing small eyes near posterior edge, posterior margin broadly “V” shaped and embedded into first pereomere. Antennae of 3 and 7, articles respectively, both sparsely setose distally ( Fig. 2N ). Second antenna much longer than first antenna, extended far beyond margin of head and visible in dorsal view ( Fig. 2L, M ).

Pereomeres almost equally wide, seventh pereomere slightly broadest, their margins broadly rounded and notched anterolaterally. Small midventral projections on pereomeres 2–7 ( Fig. 2M ). Pereopods 1–2 larger than others, dactyli of first two pereopods much larger and more sharply pointed and propodi somewhat larger than those of posterior pereopods, other articles all of about same size ( Fig. 2O, P ).

Pleon of 6 pleomeres, each narrower than that before it, without midventral projections. Pleomeres 1–4 distinct, pleomeres 5–6 fused dorsally but with segmentation indicated by lateral indentations and partial ventral suture. Four pairs of oval flaplike uniramous pleopods lying against surface of pleomeres. No fifth pleopods or uropods.

Etymology. — The specific name arrosor , a Latin noun used in apposition, means “sponger” or “one who lives at the expense of another.” It has been selected because it is the species name of the new species’ host, Dardanus arrosor (Herbst, 1796) . The word arrosor can also mean “parasite,” so its selection seems more appropriate here than in the original use for the host species.

Remarks. — Pagurion arrosor , n. sp. is distinguished from its only known congener, P. tuberculata Shiino, 1933 , thus: Female: Frontal lamina of head, absent in the new species ( Fig. 2A ), well developed in P. tuberculata ( Shiino, 1933: fig. 2A). Antennae 1 and 2 of 4 and 5 articles, respectively, in P. arrosor ( Fig. 2C ), of 3 and 4 articles in P. tuberculata ( Shiino, 1933: fig. 2L). Pleomere 6 obscure in P. arrosor ( Fig. 2A ), distinct in P. tuberculata ( Shiino, 1933: fig. 2A). In males, the last two pleomeres of P. arrosor are somewhat fused ( Fig. 2L ), while those of P. tuberculata are distinctly separated.

Distribution and hosts. — South China Sea, infesting Dardanus arrosor (Herbst) . D. arrosor has been reported to host two other pseudionine (branchial) bopyrid species, Asymmetrione dardani Bourdon, 1968 in Morocco ( Bourdon, 1968) and Pagurion tuberculata (discussed above) in Australia and one athelgine (abdominal) species, Parathelges carolii Codreanu, 1968 in Italy ( Codreanu, 1968).

Figures

Fig. 1.Pagurion tuberculata Shiino, 1933: A–N, female, CIEA600401; O–U, male, CIEA600402. A, Dorsal view; B, ventral view; C, left antennae; D, left maxilliped; E, palp of same; F, left side of barbula; G, left oostegite 1, external view; H, same, internal view; I, left pereopod 7; J, left pleopod 1; K, left pleopod 2; L, left pleopod 3; M, left pleopod 4; N, left pleopod 5; O, dorsal view; P, ventral view; Q, right antennae; R, left pereopod 1; S, left pereopod 2; T, left pereopod 3; U, left pereopod 4. Scale bar = 1 mm (A, B), 0.13 mm (C, E, Q–U), 0.27 mm (D, F–H), 0.22 mm (I), 0.57 mm (J–N), 0.36 mm (O, P).

Fig. 2. Pagurion arrosor n. sp: A–K, holotype female, CIEA623801; L–P, allotype male, CIEA623802.A, Dorsal view; B, ventral view; C, left antennae; D, left maxilliped, external view; E, palp of same; F, left side of barbula; G, left oostegite 1, external view; H, left oostegite 1, internal view; I, left pereopod 1; J, left pleopod 1; K, left pleopod 5; L, dorsal view; M, ventral view; N, left antennae; O, right pereopod 1; P, pereopod 6. Scale bar = 1 mm (A, B), 0.13 mm (C, E), 0.57 mm (D), 0.31 mm (F), 0.44 mm (G, H), 0.22 mm (I), 0.67 mm (J), 0.50 mm (K), 0.36 mm (L, M), 0.12 mm (N–P).