Ceratothoa africanae, Hadfield, Kerry A., Bruce, Niel L. & Smit, Nico J., 2014

Hadfield, Kerry A., Bruce, Niel L. & Smit, Nico J., 2014, Review of the fish parasitic genus Ceratothoa Dana, 1852 (Crustacea, Isopoda, Cymothoidae) from South Africa, including the description of two new species, ZooKeys 400, pp. 1-42 : 5-7

Ceratothoa africanae sp. n. Figs 1-7, 21

Material examined.

Holotype. Female (29 mm TL; 15 mm W), collected from a trawl (34°26'S, 24°13'E) along the south coast of South Africa from the buccal-cavity of Spondyliosoma emarginatum , 30-04-2003, coll. N.J. Smit (SAM A45937; HP 221).

Paratypes. All from the buccal-cavity of Spondyliosoma emarginatum and collected while trawling (34°26'S, 24°13'E) along the south coast of South Africa (30-04-2003), coll. N.J. Smit: Three females (22-26 mm TL; 12-15 mm W), three males (11-13 mm TL; 5-6 mm W), one dissected female (30 mm TL; 15 mm W), one dissected male (16 mm TL; 7 mm W) (SAM A45938; HP 221).

Other material. In the possession of authors at NWU. From the the buccal-cavity of Spondyliosoma emarginatum : Algoa Bay (33°51'S, 25°52'E), 1978: female (28 mm TL; 12 mm W). Eastern Cape, no date: female (20 mm TL; 11 mm W), male (7 mm TL; 3 mm W). Tsitsikamma Grootbank, Sout River (34°1'S, 23°28'E), September 1993: female (19 mm TL; 8 mm W).

Ovigerous female holotype.

Length 19-29 (23.4) mm, width 8-15 (12.5) mm.

Body ovoid, 1.5 times as long as greatest width, dorsal surfaces smooth and polished in appearance, widest at pereonite 4, most narrow at pereonite 1, lateral margins posteriorly ovate. Cephalon 0.6 times longer than wide, visible from dorsal view, triangular. Frontal margin rounded to form blunt rostrum. Eyes oval with distinct margins. Pereonite 1 with slight indentations, anterior border straight, anterolateral angle with small distinct anterior projection which does not extend past the eyes, posterior margins of pereonites smooth and straight. Coxae 2-3 with posteroventral angles not visible; 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, visible in dorsal view; pleonites posterior margin smooth, mostly concave; posterolateral angles of pleonite 2 narrowly rounded, not posteriorly produced. Pleonites 3-5 similar in form to pleonite 2. Pleonite 5 with posterolateral angles free, not overlapped by lateral margins of pleonite 4, posterior margin with 2 indented points. Pleotelson 0.5 times as long as anterior width, dorsal surface smooth, lateral margins posteriorly narrow, posterior margin evenly rounded, without median point.

Antennule more stout than antenna, comprised of 7 articles; peduncle articles 1 and 2 distinct and articulated; article 2 0.9 times as long as article 1; article 3 0.3 times as long as combined lengths of articles 1 and 2, 0.7 times as long as wide; flagellum with 4 articles, extending to anterior of pereonite 1. Antenna comprised of 8 articles. Antenna peduncle article 3 1.5 times as long as article 2, as long as wide; article 4 0.8 times as long as wide, 0.8 times as long as article 3; article 5 0.5 times as long as article 4, 0.7 times as long as wide. Antenna flagellum with 3 articles, last article terminating in no setae, extending to anterior margin of pereonite 1. Anterior margin acute, with small median point. Mandibular process ending in an acute incisor, with no simple setae, mandible palp article 2 and 3 without setae. Maxillule simple with 4 terminal robust setae. Maxilla mesial lobe partly fused to lateral lobe; lateral lobe without simple setae, 3 recurved robust setae; mesial lobe with 6 large recurved robust setae and no simple setae. Maxilliped covered in pectinate scales and comprised of 3 articles, with lamellar oostegite lobe, palp article 2 without simple setae, article 3 with 5 recurved robust setae. Oostegites margin covered in numerous plumose setae, attached to pereopods 2-5.

Pereopod 1 basis 1.6 times as long as greatest width; ischium 0.7 times as long as basis; merus proximal margin with bulbous protrusion; carpus with straight proximal margin; propodus 1.3 times as long as wide; dactylus slender, 1.1 as long as propodus, 2.4 times as long as basal width. Pereopod 2 propodus 1.4 as long as wide; dactylus 1.1 as long as propodus. Pereopods gradually increasing in size towards posterior and all without robust or simple setae. Pereopod 6 basis 1.3 times as long as greatest width, ischium 0.9 times as long as basis, propodus 1.4 as long as wide, dactylus 1.3 as long as propodus. Pereopod 7 basis 1.3 times as long as greatest width; ischium 0.7 as long as basis, without protrusions; merus proximal margin with slight bulbous protrusion, merus 0.3 as long as ischium, 0.4 times as long as wide; carpus 1.3 as long as ischium, without bulbous protrusion, 0.8 times as long as wide; propodus 0.7 as long as ischium, 1.4 times as long as wide; dactylus slender, 1.3 as long as propodus, 3 times as long as basal width.

Pleopods without setae, exopod larger than endopod. Pleopod 1 exopod as long as wide, lateral margin strongly convex, distally truncate, mesial margin weakly convex; endopod 1.2 times as long as wide, lateral margin convex, distally subtruncate, mesial margin straight; peduncle 3.3 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. Large medial lobes present and increasing in size from pleopod 1 to 5.

Uropod more than half the length of pleotelson, peduncle 0.7 times longer than rami, peduncle lateral margin without setae; rami not extending beyond pleotelson, marginal setae absent, apices narrowly rounded. Endopod apically slightly pointed, 3.8 times as long as greatest width, lateral margin straight, terminating without setae, mesial margin straight. Exopod not extending to end of endopod, 4.1 times as long as greatest width, apically rounded, lateral margin weakly convex, terminating with no setae, mesial margin straight.

Male.

Length 7-14 (10.6) mm, width 3-7 (4.9) mm.

Males similar to females but much smaller. Body oval, 1.4 times as long as wide. Penis small, low tubercles. Pleopod 2 appendix masculina with parallel margins, 1.2 times as long as endopod, distally bluntly rounded.

Etymology.

Named for FRS Africana, from which the species was collected, also acknowledging that this is the first Ceratothoa species to be described from Africa.

Distribution.

Eastern Cape Province, South Africa: from Tsitsikamma to Algoa Bay.

Hosts.

Found in the buccal-cavity, on the tongue of Spondyliosoma emarginatum (Valenciennes, 1830).

Prevalence.

9/17 (53%) of Spondyliosoma emarginatum infected from the FRS Africana trawls, 4/68 (5.9%) from the SAIAB collections.

Remarks.

Ceratothoa africanae sp. n. can be distinguished by the stout body shape of the female; a pointed rostrum; short and stout antennae; uropods which do not extend past the pleotelson; a broad pleon; large medial lobes on female pleopods; and an appendix masculina on the second pleopod in male specimens. This species was compared to the known species from South Africa at the time ( Ceratothoa imbricata , Ceratothoa retusa and Ceratothoa trigonocephala ) and found to be distinct. Upon comparisons to other known species worldwide, it was concluded to be a new species.

Ceratothoa africanae sp. n. differs from Ceratothoa retusa in having a larger cephalon not sunken into pereonite 1 as seen in Ceratothoa retusa ; lacks the anterolateral ridge on pereonite 1; has shorter uropods which do not extend past the posterior margin of the pleotelson; and lacks the large extended anterolateral margins on pereonite 1 which extend more than half the length of the cephalon in Ceratothoa retusa but less than half in Ceratothoa africanae .

Ceratothoa africanae sp. n. shares many similarities with Ceratothoa imbricata and Ceratothoa famosa sp. n. Ceratothoa africanae resembles Ceratothoa imbricata in having pereonite 1 longer than pereonites 2-4 and both have two concave mediolateral indents on the pleonite 5 posterior margin, but differs in having a broader body, anterolateral angles on pereonite 1 which do not extend past the eyes as is seen in Ceratothoa imbricata , shorter uropods that do not extend past the pleotelson and an acute cephalon anterior margin. The pleopods of Ceratothoa africanae have a few smaller lobes and folds and the pereopod 6 and 7 merus is produced on both the anterior and posterior sides. Furthermore, Ceratothoa africanae pereonite 7 does not overlap any pleonites and pereopods 1 to 3 have a smaller merus, but pereopods 4 to 7 are larger. Ceratothoa africanae and Ceratothoa famosa (see below) differ in the number of setae on the mandibular palp (five on Ceratothoa africanae and three on Ceratothoa famosa ); no setae on the maxilliped palp in Ceratothoa africanae sp. n. but seven setae on Ceratothoa famosa ; and nine setae on Ceratothoa africanae maxilla but ten on Ceratothoa famosa . More differences are noted in the remarks on Ceratothoa famosa sp. n.