Cymothoa sodwana, Hadfield, Kerry A., Bruce, Niel L. & Smit, Nico J., 2013

Hadfield, Kerry A., Bruce, Niel L. & Smit, Nico J., 2013, Review of the fish-parasitic genus Cymothoa Fabricius, 1793 (Isopoda, Cymothoidae, Crustacea) from the southwestern Indian Ocean, including a new species from South Africa, Zootaxa 3640 (2), pp. 152-176 : 164-165

Cymothoa sodwana sp. nov.

( Figs 6–12 )

Material examined. Holotype ( Figs. 6–9 ). Ƥ (22 mm TL; 13 mm W), from the buccal cavity of Trachinotus botla from Sodwana Bay, South Africa (27°32ʹS, 32°41ʹE), 28 March 2010, coll. K.A. Hadfield. (SAMC A45926).

Paratypes ( Figs. 10–12 ). Ƥ (21 mm TL; 13 mm W - dissected), two 3 (12, 13 mm TL; 7 mm W), from the buccal cavity of Trachinotus botla from Sodwana Bay, South Africa (27°32ʹS, 32°41ʹE), 28 March 2010 (SAMC A45927 ).

Other material. Four Ƥ (27, 25, 23, 17 mm TL; 15, 13, 14, 12 mm W), four 3 (14, 14, 13, 12 mm TL; 7, 7, 7, 6 mm W), one juvenile (7 mm TL; 3 mm W) removed from the buccal cavity of Trachinotus botla (SAIAB 8944; SAIAB 46696) from Sodwana Bay, South Africa (27°32ʹS, 32°41ʹE), April 1979 (SAMC A45928 ).

Type host. Trachinotus botla (Shaw, 1803) .

Description. Ovigerous female, length 17–27 (22.9) mm, width 12–15 (14.2) mm.

Body ovoid, 1.2 times as long as greatest width, dorsal surfaces rugose, widest at pereonite 4, most narrow at pereonite 1, lateral margins posteriorly ovate. Cephalon 0.7 times longer than wide, slightly visible in dorsal view. Frontal margin rounded to form blunt rostrum. Eyes not visible. Pereonite 1 with slight indentations, anterior border slightly indented, anterolateral angle rounded, posterior margins of pereonites smooth and slightly curved laterally. Coxae 2–3 with posteroventral angles rounded; 4–7 rounded. Pereonites 1–4 increasing in length and width; 5–7 decreasing in length and width; becoming more progressively rounded posteriorly. Pleon with pleonite 1 same width as other pleonites (except pleonite 5), visible in dorsal view; pleonites posterior margin smooth, mostly convex; posterolateral angles of pleonite 2 rounded, not posteriorly produced. Pleonites 3–5 similar in form to pleonite 2. Pleonite 5 posterior margin produced medially. Pleotelson 0.5 times as long as anterior width, dorsal surface smooth, lateral margins weakly concave, posterior margin sub-truncate, without median point.

Antennule more stout than antenna, comprised of 8 articles; peduncle articles 1 and 2 distinct and articulated; article 2 1 times as long as article 1; article 3 0.6 times as long as combined lengths of articles 1 and 2, 1.2 times as long as wide; flagellum with 5 articles. Antenna comprised of 8 articles; peduncle article 3 1.5 times as long as article 2, 1.8 times as long as wide; article 4 1.1 times as long as wide, 0.7 times as long as article 3; article 5 0.8 times as long as article 4, 0.9 times as long as wide; flagellum with 3 articles, last article terminating in 1–5 short simple setae. Labrum anterior margin anteriorly truncate, without small median point. Mandibular process without simple setae, mandible palp article 2 without distolateral setae, article 3 without serrate setae. Maxillule simple, with 4 terminal robust setae. Maxilla mesial lobe partly fused to lateral lobe; lateral lobe without simple setae, and 4 recurved robust setae; mesial lobe without simple setae, and 3 large recurved robust setae. Maxilliped comprised of 3 articles or weakly segmented, with lamellar oostegite lobe, palp article 2 without simple setae, article 3 with 8 recurved robust setae, and no simple setae. Oostegites margin covered in numerous plumose setae, attached to pereopods 3–6.

Pereopod 1 basis 2.2 times as long as greatest width; ischium 0.6 times as long as basis; merus proximal margin without bulbous protrusion; carpus with straight proximal margin; propodus 1.5 times as long as wide; dactylus slender, 1.2 as long as propodus, 2.5 times as long as basal width. Pereopod 2 propodus 1.5 as long as wide; dactylus 1.1 as long as propodus. Pereopod 3 similar to pereopod 2. Pereopod 6 basis 1.3 times as long as greatest width, ischium 0.7 times as long as basis, propodus 1.2 as long as wide, dactylus 1.4 as long as propodus. Pereopod 7 basis 1.2 times as long as greatest width; ischium 0.7 as long as basis, with large proximal bulbous protrusion; merus proximal margin without bulbous protrusion, merus 0.3 as long as ischium, 0.5 times as long as wide; carpus 1.3 as long as ischium, with slight bulbous protrusion, 0.6 times as long as wide; propodus 1.7 as long as ischium, 1.4 times as long as wide; dactylus slender, 1.5 as long as propodus, 2.6 times as long as basal width.

Pleopods without setae, lobes increasing in size from pereonite 1 to 5, exopod larger than endopod. Pleopod 1 exopod 1 times as long as wide, lateral margin weakly convex, distally broadly rounded, mesial margin straight; endopod 1.2 times as long as wide, lateral margin weakly concave, distally narrowly rounded, mesial margin straight, peduncle 0.4 times as wide as long, without retinaculae. Pleopods 2–5 similar to pleopod 1 and mesial margins becoming more strongly produced. Pleopods 3–5 endopods proximal borders extending below exopod to peduncle, with large fleshy folds and medial lobes present and increasing in size from pleopod 1 to 5.

Uropod more than half the length of pleotelson, peduncle 1.1 times longer than rami, peduncle lateral margin without setae; rami not extending beyond pleotelson, marginal setae absent, apices narrowly rounded. Endopod apically rounded, 3.1 times as long as greatest width, lateral margin weakly convex, terminating with no setae, mesial margin weakly convex. Exopod extending to end of endopod, 3.5 times as long as greatest width, apically rounded, lateral margin weakly convex, terminating with no setae, mesial margin weakly convex.

Male. Length 6.0–14.0 mm (11.8 mm), width 2.0–7.0 mm (5.8 mm).

Males similar to females but smaller, body oval, body 1.3 times as long as wide. Cephalon visible in dorsal view, with slightly produced anterolateral margins on pereonite 1. Pleopods simple, with less folds on endopod. Pleopod 2 appendix masculina with parallel margins, 0.9 times as long as endopod, distally acute.

Distribution. Currently only known from the type locality, Sodwana Bay, northeastern South Africa.

Host. Trachinotus botla is found in the Western Indian Ocean from Oman to Algoa Bay.

Etymology. The epithet is the name of the type locality, Sodwana Bay; noun in apposition.

Remarks. Cymothoa sodwana sp. nov. is distinguished by the large, ovoid body and rugose dorsal surfaces; anterolateral angles of pereonite that are narrow and rounded reaching half the length of the cephalon; uropods which do not reach the posterior margin of the pleotelson; pleopods with large fleshy folds as well as proximomedial and peduncle lobes; large protrusion on ischium of pereopod 7; setae on antennae; and pereonite 7 which overlaps the pleon, extending posteriorly to the pleotelson.

Kensley (1978) included one species of Cymothoa as known from South Africa, namely C. borbonica . When comparing Cymothoa sodwana to C. borbonica , a number of differences can be seen. Cymothoa sodwana has a more robust body, compared to the more elongate shape of C. borbonica , and is more dorsally vaulted. Cymothoa sodwana also has more produced posterolateral margins on pereonites 5–7 with pereonite 7 overlapping the pleon and reaching the pleotelson. Cymothoa borbonica does not have developed posterolateral margins at all. Pereonite 1 of C. sodwana is longer and not produced on the lateral margins compared to C. borbonica . Cymothoa borbonica has a more inwardly produced anterior margin of pereonite 1 with wide and pointed anterolateral margins which are not seen in Cymothoa sodwana (almost straight anterior border and bluntly rounded anterolateral margins).

A total of 22 Trachinotus botla fish specimens were caught at Sodwana Bay, 16 of which were parasitised by Cymothoa sodwana giving a high prevalence of 72.7%. During the sampling of the preserved fish in SAIAB, another 23 T. botla were examined but only four were still infested with the isopod (5.9%).

Figures

FIGURE 6. Cymothoa sodwana sp. nov. Female holotype (22 mm) (SAMC A 45926). A, dorsal view; B, ventral view of cephalon; C, antero-dorsal view of pereonite 1 and cephalon; D, dorsal view of pleotelson; E, lateral view.

FIGURE 7. Cymothoa sodwana sp. nov. Female paratype (21 mm) (SAMC A 45927). A, antennule; B, antenna; C, mandible; D, maxillule; E, maxilla; F, maxilliped with oostegite; G, tip of maxilliped article 3; H, uropod; I, oostegites.

FIGURE 8. Cymothoa sodwana sp. nov. Female paratype (21 mm) (SAMC A 45927). A, pereopod 1; B, pereopod 2; C, pereopod 6; D, pereopod 7.

FIGURE 9. Cymothoa sodwana sp. nov. Female paratype (21 mm) (SAMC A 45927). A, dorsal pleopod 1; B; dorsal pleopod 2; C, dorsal pleopod 3; D, dorsal pleopod 4; E, dorsal pleopod 5, F, ventral pleopod 1; G, ventral pleopod 2; H, ventral pleopod 3; I, ventral pleopod 4; J, ventral pleopod 5.

FIGURE 10. Cymothoa sodwana sp. nov. Male paratype (13 mm) (SAMC A 45927). A, dorsal view; B, dorsal view of pleotelson; C, uropod; D, dorsal view of pleotelson; E, lateral view.

FIGURE 11. Cymothoa sodwana sp. nov. Male paratype (13 mm) (SAMC A 45927). A, antennule; B, antenna; C, maxilliped; D, mandible; E, maxilla; F, tip of maxillule; G, pereopod 1; H, pereopod 7.

FIGURE 12. Cymothoa sodwana sp. nov. Male paratype (13 mm) (SAMC A 45927). A, dorsal pleopod 1; B; dorsal pleopod 2; C, dorsal pleopod 3; D, dorsal pleopod 4; E, dorsal pleopod 5, F, ventral pleopod 1; G, ventral pleopod 2; H, ventral pleopod 3; I, ventral pleopod 4; J, ventral pleopod 5.