Mothocya powelli, Wal & Smit & Bruce & Olaosebikan & Hadfield, 2021

Wal, Serita van der, Smit, Nico J., Bruce, Niel L., Olaosebikan, Babatunde & Hadfield, Kerry A., 2021, Two new species of branchial fish parasitic isopod of the genus Mothocya Costa, in Hope, 1851 (Isopoda, Cymothoidae) from Nigeria, International Journal for Parasitology: Parasites and Wildlife 15, pp. 1-11 : 8-9

3.2. Mothocya powelli n sp

Fig. 7

3.2.1. Material examined

Holotype. Female (ovigerous, 7.0 mm total length, 5.0 mm width; dry) from Birakiki (4 ◦ 34 ′ 10 ′′ N, 7 ◦ 08 ′ E), host unknown, seaward end of Hughes Channel, Bonny River (ca 15 km NNW of Bonny Town), Nigeria, December 1985, coll. CB Powell and B Olaosebikan ( SAMC-A092739 ).

ZooBank registration: The Life Science Identifier ( LSID) of the article is urn:lsid:zoobank.org:pub:38FB6597-830B-45AA-A8BF-A692B39F765C . The LSID for the new name Mothocya powelli n. sp. is urn:lsid:zoobank.org:act:D31760A8-8AFC-44E1-8D98-94A28BAD740D .

3.2.2. Description ovigerous ♀ (holotype)

Body ovoid, slightly twisted to the right, 1.4 times as long as greatest width; dorsum weakly convex; widest at pereonite 5, most narrow at pereonite 1. Cephalon anteriorly sub-truncate, 0.7 times longer than wide, visible in dorsal view, immersed in pereonite 1, medially concave; frontal margin thickened, ventrally folded. Eyes oval with distinct margins; one eye 0.3 times width of cephalon, 0.4 times length of cephalon. Pereonite 1 with slight indentations, anterior border straight, anterolateral angles broadly rounded, extending past the medial region of eyes. Pereon lateral margins mostly ovate posteriorly, medially indented; posterior margins mostly straight, smooth, pereonite 7 medially recessed. Pereonites 1–4 increasing in length and width; 5–7 decreasing in length and width; 3–5 subequal. Coxae 2–3 with posteroventral angles right-angled; 4–7 rounded, large and produced. Coxae not extending past pereonite posterior margins. Pleon 0.4 times as long as total body length, with pleonite 1 largely concealed by pereonite 7; pleonites posterior margin smooth, mostly concave. Pleonite 2 partially overlapped by pereonite 7. Pleonites 3–5 similar in form to pleonite 2; pleonite 5 widest, lateral margins overlapped by pereonite 7, posterior margin straight. Pleotelson triangular, 0.7 times as long as anterior width, with anteromedial furrow, lateral margins straight, posterior margin converging to blunt caudomedial point.

Antennula consists of 5 articles; peduncle articles 1 and 2 distinct and articulated; extending to middle of eye. Antenna consisting of 5 articles, extending to middle of the eye.

Pereopod 1 basis 1.8 times as long as greatest width; ischium 0.6 times as long as basis; carpus with rounded proximal margin; propodus 1.4 times as long as wide; dactylus slender, 1.7 times as long as propodus, 3.5 times as long as basal width. Pereopod 7 basis 2.2 times as long as greatest width; ischium 0.7 times as long as basis; merus 0.9 times as

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long as wide, 0.5 times as long as ischium; carpus 0.9 times as long as wide, 0.4 as long as ischium; propodus 2.1 times as long as wide, as long as ischium; dactylus slender, 1.2 times as long as propodus, 3 times as long as basal width.

Uropod same length as pleotelson, peduncle 0.6 times longer than rami, peduncle lateral margin without setae; rami extending to pleotelson apex, apices broadly rounded. Uropod endopod 3.5 times as long as greatest width, lateral margin straight, mesial margin straight, without setae. Uropod exopod extending beyond end of endopod, 6.2 times as long as greatest width, 1.9 times as long as endopod; lateral margin straight, mesial margin straight, without setae.

Etymology. Named in honour of the late Prof C. B. Powell who was a foremost ecological expert on the fauna of Niger Delta, Nigeria.

Remarks. Mothocya powelli n. sp. can be recognised by its small size (7 mm); posteriorly ovoid body shape; blunt anterior margin of the cephalon; large eyes; antennulae and antennae with five articles; triangular pleotelson; short pleon with all pleonite lateral margins overlapped by pereonite 7; and slender uropods reaching the posterior margin of pleotelson.

This species can be distinguished from Mothocya andoni n. sp. by the notable difference in size ( M. andoni n. sp. is 15–18 mm; M. powelli n. sp. is 7 mm, based on the single specimen available; see Fig. 8 ); body posteriorly ovoid (in contrast to the medially ovoid M. andoni n. sp.); pereonite 7 overlapping the lateral margins of all pleonites (only overlaps the lateral margins of pleonites 3–4 in M. andoni n. sp.); triangular pleotelson (broadly rounded pleotelson in M. andoni n. sp.); and the uropod exopod is almost twice as long as the endopod (1.6 times as long as endopod in M. andoni n. sp.).

Figures

Fig. 7. Mothocya powelli n. sp. holotype ♀ (ovigerous, 7.0 mm total length, 5.0 mm width) (SAMC–A092739). A, Dorsal body; B, Lateral body; C, Oostegites; D, Dorsal view of cephalon with pereonite 1; E, Uropod; F, Ventral cephalon; G, Dorsal view of pleon; H, Pereopod 1; I, Pereopod 7.

Fig. 8. A, Dorsal view of Mothocya andoni n. sp. holotype ♀ (ovigerous, 15.0 mm total length, 8.0 mm width) (SAMC–A092737) (top) and Mothocya powelli n. sp. holotype ♀ (ovigerous, 7.0 mm total length, 5.0 mm width) (SAMC–A092739) (bottom); B, Ventral view of Mothocya andoni n. sp. holotype ♀ (top) and Mothocya powelli n. sp. holotype ♀ (bottom); C, Dorsal view of Mothocya andoni n. sp. holotype ♀ (left) and Mothocya andoni n. sp. Ƌ (12.0 mm total length, 5.0 mm width) (SAMC–A092738) (right).