Ione thompsoni Richardson, 1904

Boyko, Christopher B., Williams, Jason D. & Shields, Jeffrey D., 2017, Parasites (Isopoda: Epicaridea and Nematoda) from ghost and mud shrimp (Decapoda: Axiidea and Gebiidea) with descriptions of a new genus and a new species of bopyrid isopod and clarification of Pseudione Kossmann, 1881, Zootaxa 4365 (3), pp. 251-301 : 255-256

Ione thompsoni Richardson, 1904

Fig. 1A–C

Ione thompsoni Richardson, 1904: 75 –78, figs. 64–68 (2 specimens, type locality: North Falmouth, Massachusetts, infesting Callianassa stimpsoni Smith, 1873 = Gilvossius setimanus (DeKay, 1844)) .— Giard, 1904: 592 (mention).— Rathbun, 1905: 49 (list).— Richardson, 1905: 508 –510, figs. 554–558 (repeat of 1904 text; no new material).— Giard, 1913: 420 (mention).— Sumner et al., 1913: 661 (list).— Kunkel, 1918: 192 (mention of specimens examined herein in a footnote).— Chopra, 1923: 437 (mention).—Nierstrasz & Brender à Brandis, 1923: 80 (list).— Miner, 1950: 451, pl. 145 (list; brief description with figures from Richardson, 1904).— Danforth, 1963a: 8 (list).— Shiino, 1964a: 32 (mention).— Smith & Bowman, 1964: 105, 107, 108, pl. 14, fig. 20 (list, figure after Richardson, 1904).— Schultz, 1969: 316, fig. 502 (list, figure after Richardson, 1904).— Danforth, 1970b: 10, 47 (list), 147 (key), fig. 22d–f (after Richardson, 1905).— Kaestner, 1970: 462 –463 (mention occurrence “on Callianassa on the eastern North American coast”).— Gosner, 1971: 476 (list).— Lawler, 1978: 309 (list).— Markham, 1988: 56 (list).— Adkison & Heard, 1995: 108 (mention).— Markham, 1995: 86 (mention).— Markham, 2001: 199, 200 (list).— Heard et al., 2007: 22 (mention of specimens from Georgia and Florida).

“Crustacean lice” Pimentel, 1967: 89, 2 unnumbered figures (after Richardson, 1904).

Material examined. United States: Mature female (17.9 mm), mature male (5.3 mm) ( YPM IZ 089393), ex left branchial chamber of female Gilvossius setimanus (15.6 mm CL) ( YPM IZ 005658.CR), Long Island Sound, outer island, Thimble Islands, Branford, New Haven County, Connecticut, 4–6 ft (1.2–1.8 m), coll. A. E. Verrill, 17 May 1910.

Distribution. North Falmouth, Massachusetts to Long Island Sound; and possibly to St. Augustine, Florida.

Host. Gilvossius setimanus (DeKay, 1844) (type host).

Remarks. The specimens from Long Island Sound match the original description of Ione thompsoni , with females possessing highly digitate lateral plates, five pairs of biramous pleopods, and large, slightly curled, uniramous uropods ( Fig. 1A, B ); the oostegites are covered in short, thin cuticular extensions ( Fig. 1B ). Males are found attached between the pleopods ( Fig. 1B ) and have long, lanceolate lateral plates ( Fig. 1C ). Ione thompsoni is a rare bopyrid, with the pair of specimens reported herein first being mentioned without description or illustration in a footnote in Kunkel (1918) and only now having their identity verified, nearly 100 years later. This rarity is surprising considering the relatively large size of the host, Gilvossius setimanus , and its distribution in the wellstudied fauna of the shallow water, northeastern American coastal region. The range of the host is from Nova Scotia to southern Georgia ( Heard et al. 2007), whereas that of I. thompsoni is apparently from Cape Cod, Massachusetts to northern Florida. However, the only records of I. thompsoni from outside Massachusetts (type locality) and Long Island Sound (present specimens) are from Georgia and Florida but with both as “pers. observ.” cited in Heard et al. (2007); these specimens are not known to have been deposited in any museum collection and are not described or illustrated. Although Heard et al. (2007) stated that the southern end of the range of the host was Georgia, they also mentioned a parasitized host from St. Augustine, Florida, without comment that such a record would extend the known host range somewhat farther south. Williams (1984) gave the host range as extending to Franklin County, Florida, but this locality is in the Florida panhandle; Manning and Felder (1991) suggested that specimens from the northeastern Gulf of Mexico might belong to an undescribed species of Gilvossius . No bopyrids have been reported from specimens of Gilvossius from the Gulf of Mexico.

Richardson (1904) described the species based on “two specimens… collected by Mr. G. M. Gray at North Falmouth , Massacusetts ” and listed the “ type ” as USNM 29091 . However, it is clear that Richardson (1904) had at least three specimens on hand because she described both the male and female of the species, but also mentioned a “young female” and an “adult female” (p. 75, footnote) . USNM 29091 is the female holotype, whereas USNM 29230, also labeled as being collected from the type locality by Gray, contains one female and one male, both of which are paratypes.

Figures

FIGURE 1. A–C, Ione thompsoni Richardson, 1904 (YPM IZ 089393) ex Gilvossius setimanus (DeKay, 1844)). A, dorsal overview of female; B, ventral overview of female with male in situ; C, ventral overview of male. D, photograph of live male Callianassa truncata Giard & Bonnier, 1890 (NHMW 20514) from Croatia bearing Ione thoracica (Montagu, 1808) (NHMW 25810) in left branchial chamber. Scale bars:A–C = 2 mm; D = 5 mm.D courtesyof Peter Dworschak.