Cymothoa eremita ( Brünnich, 1783 ), Brunnich, 1783

Martin, Melissa B., Bruce, Niel L. & Nowak, Barbara F., 2016, Review of the fish-parasitic genus Cymothoa Fabricius, 1793 (Crustacea: Isopoda: Cymothoidae) from Australia, Zootaxa 4119 (1), pp. 1-72 : 18-24

Cymothoa eremita ( Brünnich, 1783)

Figures 9–13

Oniscus oestrum .— Spengler 1775: 312, pl. 7 (figs. i–k).

Oniscus eremita Brünnich, 1783: 319 .

Cymothoa Leschenaultii Leach, 1818: 352 .— Desmarest, 1825: 309.

Cymothoa Mathoei Leach, 1818: 353 ; Desmarest, 1825: 309.

Cymothoa mathoei .— Milne Edwards, 1840: 270.— Hilgendorf, 1869: 114.— Gerstaecker, 1901: 182, 258.

Cymothoa leschenaultii .— White, 1847: 109.— Miers, 1880: 461.— Ellis, 1981: 124.

Cymothoa matthaei [sic].— White, 1847: 110.— Bleeker, 1857: 22.

Cymothoa mathaei .— Lucas, 1850: 248.— Kossmann, 1880: 117, pl. 10 (figs. 1–3).

Cymothoa edwardsii Bleeker, 1857: 21 , 33, tab. II, fig. 12.— Miers, 1880: 461.— Gerstaecker, 1901: 261.

Cymothoa stromatei Bleeker, 1857: 21 , 33, 35 tab II, fig. 13.— Miers, 1880: 461.— Gerstaecker, 1901: 181.— Lanchester, 1902: 377.— Richardson, 1910: 22.— Hale, 1926: 214, fig. 9h.— Brian & Dartevelle, 1949: 184.— Sachlan, 1952: 41, 50 photo 28.— Pillai, 1954: 15.

Cymothoa eremita .— Schioedte & Meinert, 1884: 259, tab. VII (Cym. XXV), figs. 3–13.— Stebbing, 1893: 354; 1910: 102.— Gerstaecker, 1901: 182.— Thielemann, 1910: 39, figs. 37, 38, tab. 4.— Nierstrasz, 1915: 90; 1931: 135, pl. 10, fig. 9.— Monod, 1924: 100; 1933: 195; 1976: 859, figs. 23–25.— Boone, 1935: 215, pl. 63.— Shiino, 1951: 81 figs. 2 (b–c).— Avdeev, 1978a: 30; 1982b: 69.— Trilles, 1975: 987, pl. II (12–13); 1979b: 261; 1986: 627, tab. 1; 1994: 139; 2008: 23.— Bowman & Tareen, 1983: 25, fig. 20.— Radhakrishnan & Nair, 1983: 96, 105, 107.— Saito, Itani & Nunomura, 2000: 65.— Shireen, 2000: 21, figs. 1–3.— Kensley, 2001: 232.— Yu & Li, 2003a: 228, fig. 4; 2003b: 267.— Trilles & Bariche, 2006: 228.— Williams & Bunkley-Williams, 2009: 557.— Trilles, Ravichandran & Rameshkumar, 2011: 446.— Rameshkumar, Ravichandran & Trilles, 2012: 191.— Hadfield, Bruce & Smit, 2013: 158 , figs. 3–5.

Cymothoa limbata Schioedte & Meinert, 1884: 248 , tab. VII (Cym. XXV), figs. 1, 2.— Hale, 1926: 214.— Nierstrasz, 1931: 136. — Bruce, Lew Ton & Poore, 2002: 175 [new synonymy].

Cymothoa edwardsi .— Nierstrasz, 1931: 135.

Cymothoa sp. (an. eremita Brünnich, 1783 ) [sic].— Monod, 1934: 13, pl. 27 (a–b), pl. 30 (b).

Cymothoa erimitae (typographical error?).— Sachlan, 1955: 31.

Cymothoa cinerea Bal & Joshi, 1959: 567 , pl. 2, figs. 1–5.— Kensley, 2001: 232.

Cymothoa cinerius .— Joshi & Bal, 1960: 446.

Cymothoa mathieui .— Ellis, 1981: 124.

Cymothoa leaschenaultii [sic].— Kensley, 2001: 232.

Cymothoa epimerica . — Trilles, 2008: 23 (SMF-567).

Type material. Holotype: 1 non-ovig. ♀ (26 mm), from the buccal cavity of black pomfret Parastromateus niger (Bloch, 1795) , (ZMUC-CRU-10078). Not examined, see Hadfield et al. 2013 for further details.

Material examined. 1 non-ovig. ♀ (34 mm), near Bathurst Island, Northern Territory, 18 April 1988, from gold-banded jobfish Pristipomoides multidens (Day, 1871) , coll. M. Pearce (MTQ W30413).

1 ovig. ♀ (31 mm), no additional information (AM P8689). 1 ovig. ♀, 30 mm, provenance presumed to be New Guinea; no additional information (AM P9609). The specimens (AM P8689 and AM P9609) were previously examined by Herbert M. Hale without additional data (see remarks for further discussion).

Digital image from the Senckenberg Research Institute: 1 ♀ ovig. (18 mm), 1 immature ♂ (11 mm), Red Sea (SMF-567), without additional information.

Diagnosis and description. Hadfield et al. (2013) provided a detailed diagnosis and description of the type material. We include here illustrations and a brief diagnosis of the Australian female specimen only (MTQ W30413).

Body subrectangular, 1.7 times as long as greatest width, dorsal surface rugose, laterally sub-parallel, widest at pereonite 6, most narrow at pereonite 1. Cephalon subtruncate, 0.4 times longer than wide, visible from dorsal view. Eyes partially visible. Pereonite 1 anterolateral margins minute, not reaching anterior margin of cephalon; pereonites 1–4 subequal in length and width length, posterior margin linear; pereonites 5–7 subequal in length. Coxae 2–3 posteroventral margins subtruncate; 4–7 without acute carinae. Pleonite 1 narrower than pleonites 2–5, visible in dorsal view; pleonites 1–5 with irregular posterior margin; pleonites 3–5 progressively increasing in width. Pleotelson subtruncate, 0.3 times as long as anterior width, anterior margin irregular, lateral margins concave, posterior margin straight, without median point. Pereopods 1 and 2 dactyli slender; carpus proximal margin straight; merus proximal margin with slight bulbous protrusion; basis superior proximal basis without acute carinae. Pereopods 3–5 similar to pereopod 2, gradually increasing in size, without robust or simple setae. Pereopods 6 and 7 superior proximal basis with broad and acute carinae; merus proximal margin with slight bulbous protrusion; dactyli slender.

Size. Ovigerous females: 19–44 mm; non-ovigerous females: 17–35; males: 9–24 mm; second pullus: 2 mm ( Schioedte & Meinert 1884; Bal & Joshi 1959; Monod 1976; Trilles 1979b; Shireen 2000).

Remarks. Hadfield et al. (2013) redescribed and diagnosed C. eremita from the female holotype (ZMUC- CRU-10078). C. eremita can be identified by pereonite 1 anterolateral margins extending nearly half the length of cephalon; cephalon subtruncate; pleon as wide as pereon; uropods not extending to pleotelson posterior margin; pereopod 7 with a bulbous protrusion on ischium; and small horn-like structures on the posterolateral margins of pereonite 1.

Cymothoa eremita is morphologically variable (see Hadfield et al. 2013). The holotype of C. eremita (ZMUC- CRU-10078) has a subtriangular body, 2.7 times longer than wide, body widest at pereonite 6; pleon not immersed in pereonite 7; and the smooth carina on pereopod 7 basis (1.7 times longer than its greatest width). The female syntype of Cymothoa mathoei (NHMUK 1979.407.2) has a subparallel body, 2.4 times longer than wide; a raised dorsal median longitudinal ridge; pleon immersed in pereonite 7; and pereopod 7 basis with an irregular carina, which is 1.3 times longer than its greatest width. The holotype of Cymothoa leschenaultii differs from the previous mentioned specimens by having a more ovoid body shape, 2.1 times longer than wide, body widest at pereonite 5; pleonite posterior margins noticeably more trisinuate, pereonite 7 moderately laterally encompasses pleon and a highly raised carina on pereonite 7 basis, 1.0 times longer than its greatest width.

The extent to which variation in this species is either regional, host mediated or both is still not apparent, as indicated by variations in the specimens allocated to C. eremita by Hadfield et al. (2013). The Australian specimen is most similar to the syntype specimen of C. mathoei (illustrated by Hadfield et al. 2013). The Australian specimen has a wider body, 1.7 times longer than wide (as opposed to 2.4 times longer than wide); irregular posterior margins of the pleonites; more visible cephalon with anterolateral margins of pereonite 1 minute; and a slightly raised carina on pereopod 7 basis.

Among Hale’s specimens held at the South Australian Museum, we discovered a specimen of “ C. stromatei ” without host and locality data (AM P9609). Hale (1926) indicated he examined a specimen from New Guinea and briefly compared C. stromatei to C. vicina Hale, 1926 stating that both species have a subtruncate cephalon anterior margin. Hale (1926) did not mention examining the type specimens of Cymothoa stromatei Bleeker, 1857 (from “ Batavia ” = Java). The close agreement of Hale’s (1926) figures of C. stromatei to our Northern Territory material figured here suggests that the specimen is that which he examined from New Guinea. The specimens from New Guinea and Australia are very similar, the only variation noted is the more prominent anterolateral margins of pereonite 1 in Hale’s New Guinea specimen.

Trilles (1994) originally proposed the synonymy of Cymothoa limbata Schioedte & Meinert 1884 with C. eremita . Hadfield et al. (2013) also noted the strong resemblance of pereonite 1 and the pleon morphology of the two species. Cymothoa limbata resembles our examined specimens in cephalon, pereon, pleon and pleotelson morphology, and we maintain the synonymy of C. limbata with C. eremita .

Distribution. Known from the Indian Ocean and Indo-Pacific regions. For locality details see Hadfield et al. (2013) and Trilles (1994, 2008).

Hosts. Present study from Lutjanidae . Known from 10 host families (family Aulopidae , Carangidae , Haemulidae , Mugilidae , Psettodidae , Serranidae , Siganidae , Sphyraenidae , Stromateidae , Tetraodontidae ). For fish host species details, see Hadfield et al. (2013).

Figures

FIGURE 9. Cymothoa eremita, male (34 mm; MTQ W 30413) A, dorsal view; B – E, pereopods 1, 2, 6, 7 respectively; F, ventral view.

FIGURE 10. Cymothoa eremita ovigerous female (30 mm; AM P 9609). A, dorsal view; B, front view of pereonite 1 and cephalon; C, ventral view of mouthpart; D, antennula; E, antenna; F, lateral view.

FIGURE 11. Cymothoa eremita ovigerous female (30 mm; AM P 9609). A – D, pereopods 1, 2, 6, 7 respectively; E, uropod.

FIGURE 12. Cymothoa eremita, female (18 mm; SMF- 567) A, dorsal view; B, lateral view; C, ventral view. (picture credit Sven Tränkner, Senckenberg Research Institute).

FIGURE 13. Cymothoa eremita, male (11 mm; SMF- 567) A, dorsal view; B, ventral view; C, lateral view. (picture credit Sven Tränkner, Senckenberg Research Institute).