Cymothoa plebeia Schioedte & Meinert, 1884

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 : 63-67

Cymothoa plebeia Schioedte & Meinert, 1884

Figures 44–45

Cymothoa plebeia Schioedte & Meinert, 1884: 236 , tab. IX (Cym. XXVII) figs. 1, 2; Van Name, 1920: 43, 59, figs. 12, 13.— Monod, 1927: 694: 1931: 4.— Brian & Dartevelle, 1949: 84, 127, 169, 172, 176, 179, 186, figs. 92–106.— Trilles, 1975: 978, pl. I, figs. 1, 2; 1979a: 522; 1986: 627, tab 1; 1994: 147.— Rokicki, 1984a: 71, fig. 5. — Bruce, Lew Ton & Poore, 2002: 175. — Trilles & Bariche, 2006: 228.

Excluded

Cymothoa plebeia .— Avdeev, 1978b: 282 [= Cymothoa epimerica ].

Cymothoa plebeia . — Rokicki, 1985: 95, tabs. 1–3, fig. 8; 1986: 254 [= Cymothoa epimerica ].

Not Cymothoa plebeia .— Rokicki, 1984b: 60, figs. 13–16 [= Nerocila armata ].

Material examined. Holotype: 1 ovig. ♀ (21 mm), Cape Verde (type locality as “ad Promontorium viride ” by Schioedte & Meinert) unknown host ( ZMO F15977).

Ovigerous female Length 21 mm, width 9 mm (holotype).

Body subparallel, 2.2 times as long as greatest width, dorsal surface smooth, widest at pereonite 5, most narrow at pereonite 1. Cephalon 0.2 times longer than wide, visible from dorsal view, anterior margin semi-circular. Frontal margin rounded to form blunt rostrum, ventrally folded. Eyes absent. Pereonite 1 anterior margin moderately raised medially, anterolateral margins minute; pereonites 1–4 posterior margin smooth, progressively wider; pereonites 5–7 subequal in length, posterior margin moderately arched. Coxae 2–7 posteroventral margins rounded. Pleon not overlapped by pereonite 7, visible in dorsal view; pleonites posterior margin smooth; pleonites 1–4 subequal in length and width; pleonite 5 posterior margin straight. Pleotelson 0.5 times as long as anterior width, anterior margin moderately bisinuate, lateral margin weakly convex, posterior margin emarginate, without median point.

Antennula comprised of 9 articles; peduncle articles 1 and 2 distinct, not articulated; article 2 1.0 times as long as article 1; article 3 0.6 times as long as combined lengths of articles 1 and 2, 1.4 times as long as wide; extending to middle of cephalon. Antenna comprised of 9 articles, peduncle article 3 1.4 times as long as article 2, 1.6 times as long as wide; article 4 0.9 times as long as wide; article 5 0.9 times as long as article 4, terminal article without setae, extending to middle of cephalon. Labrum fleshy, lateral margins convex and produced, anterior margin rounded.

Pereopod 1 basis 1.5 times as long as greatest width, superior proximal margin smooth, without raised carina; ischium 0.7 times as long as basis; merus proximal margin without bulbous protrusion; carpus with straight proximal margin; propodus 1.8 times as long as wide; dactylus slender, 1.9 times as long as propodus, 3.2 times as long as basal width. Pereopod 2 basis 1.5 times as long as greatest width, superior proximal margin smooth, without raised carina; propodus 1.6 times as long as wide; dactylus 1.4 times as long as propodus. Pereopods 3–5 similar to pereopod 2, gradually increasing in size, without robust or simple setae. Pereopod 6 basis 1.4 times as long as greatest width, superior proximal margin smooth, with moderately raised carina; ischium 0.5 times as long as basis, propodus 1.0 times as long as wide, dactylus 1.9 times as long as propodus. Pereopod 7 basis 1.2 times as long as greatest width, superior proximal margin irregular, with raised carina; ischium 0.6 times as long as basis, without bulbous protrusion; merus proximal margin without bulbous protrusion, merus 0.2 times as long as ischium, 0.5 times as long as wide; carpus 0.3 times as long as ischium, without bulbous protrusion, 0.5 times as long as wide; propodus 0.8 times as long as ischium, 1.2 times as long as wide; dactylus stout, 1.6 times as long as propodus, 2.9 times as long as basal width.

Uropod not extending past posterior margin of pleotelson, peduncle 0.9 times as long as exopod rami, peduncle lateral margin without setae; marginal setae absent, lateral margin concave.

Colour. Light brown.

Size. Females: 13.5–25 mm; males: 6–19 mm; second pulli: 2.6–12.5 mm ( Van Name 1920; Brian & Dartevelle 1949; Trilles, 1975, 1979a; Rokicki 1984a).

Remarks. Cymothoa plebeia can be distinguished by the fleshy labrum; rounded rostrum; small and acute anterolateral margins of pereonite 1, anterior margin of pereonite 1 medially raised; pleon not immersed by pereonite 7; pereopods 6 and 7 superior proximal margin of dactyli slightly raised; pereopod 7 basis with raised carina; uropods not extending past posterior margin of pleotelson and the emarginate pleotelson that is 1.7 times wider than long.

Van Name (1920) identified and described a single male specimen (19 mm, AMNH 3236) that allowed comparison to Schioedte & Meinert’s (1884) single female specimen. Both male and female have similar body morphology, the noted differences are that the male cephalon is more visible in dorsal view, eyes partially visible (absent in female), and cephalon appearing more subtruncate.

Cymothoa indica is most similar to C. plebeia in pereonite 1, pleon, pleotelson and pereon morphology. The differences noted include C. indica having a subtriangular cephalon (compared to the more rounded anterior margins and straight lateral margins of C. plebeia cephalon); pereonite 1 anterolateral margin projecting forward (anterolateral margin curved inward to cephalon in C. plebeia ); pereopod 7 ischium with a prominent lobe on the inferior distal region (not visible in C. plebeia ); and pleotelson posterior margin rounded (emarginate in C. plebeia ).

Avdeev’s (1978b) and Rokicki’s (1985, 1986) records of C. plebeia from the sparid Pagrosomus sp. are questionable. The two possible host species from the genus are Pagrus major (Temminck & Schlegel, 1843) with a northwestern Pacific distribution, and Pagrus auratus (Foster, 1801) known from the Western-Pacific. Neither host species conform to the known distribution of C. plebeia from the eastern Atlantic Ocean and therefore both Avdeev’s and Rokicki’s records of C. plebeia are here excluded from synonymy.

Distribution. Known from the eastern Atlantic Ocean and northwestern African coast: Cape Verde ( Schioedte & Meinert 1884; Van Name 1920); Congo ( Van Name 1920; Brian & Dartevelle 1949); Cameroon ( Monod 1931; Trilles 1975); Angola ( Brian & Dartevelle 1949); Benin and Ghana ( Trilles 1975); and Senegal ( Trilles 1979a; Rokicki 1984a).

Schioedte & Meinert (1884) designated the type locality as “ad Promontorium viride ” (Latin for Cape Verde). Other authors ( Brian & Dartevelle 1949; Trilles 1975, 1994; Rokicki 1984b) have refered to the location as “from Cap Vert” or “ Senegal ”.

Avdeev (1978b) recorded C. plebeia from the western coast of Australia, but did not indicate where the specimens were deposited. Like several other of Avdeev’s species, the specimens could not be located at TINRO. As there are no specimens of C. plebeia in Australian collection, and given with the restricted distribution of C. plebeia in the eastern Atlantic Ocean, we here exclude C. plebeia from the Australian fauna.

Hosts. Reported from families of Haemulidae and Sciaenidae ; bigeye grunt Brachydeuterus auritus (Valenciennes, 1832) (see Monod 1931; Trilles 1975, 1979a; Rokicki 1984a).

Figures

FIGURE 44. Cymothoa plebeia, ovigerous female holotype (21 mm; F 15977). A, dorsal view; B, ventral view of mouthpart and pereopod 1 (dactylus and propodus); C, antennula; D, antenna; E, lateral view.

FIGURE 45. Cymothoa plebeia, ovigerous female holotype (21 mm; F 15977). A – D, pereopods 1, 2, 6, 7 respectively.