Redescription of the monotypic genus Cinusa Schioedte and Meinert, 1884 (Isopoda, Cymothoidae), a buccal-cavity isopod from South Africa Author Hadfield, Kerry A. Author Bruce, Niel L. Author Smit, Nico J. text Zootaxa 2010 2437 51 68 journal article 10.5281/zenodo.194854 745169e6-7022-41cd-92c6-9016863e1baa 1175-5326 194854 Cinusa tetrodontis Schioedte and Meinert, 1884 , Figs 1–12 Cinusa Tetrodontis Schioedte and Meinert, 1884 : 313 –318, tab. XII (Cym. XXX) figs 3–7. Cinusa tetrodontis . – Stebbing, 1910 : 425 .– Nierstrasz, 1931 : 138 .– Barnard, 1940 : 491 .– Kensley, 1978: 78, fig. 32D. Material examined. Lectotype [here designated]. Ƥ 25.5 mm , Kap. S.K.M. Kapt. Cornellussen ( ZMUC CRU- 9140). Paralectotypes . Ƥ 23 mm , 2 3 17 mm, 17.5 mm , 1875, Kap. S.K.M. Kapt. Cornellussen ( ZMUC CRU- 9140). Ƥ 27 mm , 1863, Simons Bay ( ZMUC CRU- 9138), Ƥ 33 mm , 3 13 mm , East Indian Ocean ( ZMUC CRU- 9139), 66 larvae , stage 2 in mouth ( ZMUC CRU- 9141). Non-type material. All from Amblyrhynchotes honckenii and deposited in the South African Museum, Cape Town: Ƥ ( 15 mm TW, 7 mm W), 3 ( 9 mm TW, 5 mm W), Algoa Bay, 33°51'8.35"S , 25°52'24.19"E , December 1979 ( SAMC A46763). De Hoop Nature Reserve, 34°28'40.93"S , 20°31'29.86"E : 2 Ƥ (19 & 23mm TW, 13 & 14 mm W), 2 3 ( 15 mm TW, 6 mm W), November 1999 ( SAMC A46764). Ƥ ( 10 mm TW, 5 mm W), Oct 2003 ( SAMC A46765). Ƥ ( 18 mm TW, 13 mm W), 3 ( 13 mm TW, 6 mm W), November 2006 ( SAMC A46766). Ƥ ( 17 mm TW, 9 mm W), Great Fish Point, 33°29'46.88"S , 27° 8'5.04"E , April 1954 ( SAMC A46767). Ƥ ( 29 mm TW, 19 mm W), 3 ( 10 mm TW, 5 mm W), Jeffery’s Bay, 34° 02'05.71"S , 24° 56'53.38 60"E, February 2003 ( SAMC A46768). Ƥ ( 27 mm TL, 17 mm W), 3 ( 18 mm L, 8 mm W), Knysna, 34° 5'1.38"S , 23° 3'37.60"E , date not recorded (± 1971–1975 ) removed from preserved fish at SAIAB ( SAMC A46769). 3 ( 9 mm TW, 4 mm W), Tshani, 31°56'43.95"S , 29°12'34.07"E , March 1980 ( SAMC A46770). Tsitsikamma National Park, 34° 1'13.65"S , 23°52'33.23"E : 2 Ƥ (19 & 23 mm TW, 9 & 17 mm W), March 2007 ( SAMC A46771). Ƥ ( 17 mm TW, 9 mm W), 3 ( 12 mm TW, 4 mm W), March 2005 ( SAMC A46772). 3 ( 9 mm TW, 4 mm W), Umgazana, 31°41'29.27"S , 29°25'25.88"E , May 2006 ( SAMC A46773). Ovigerous female. Length 10–29 mm ( 20.1 mm ), width 5–19 mm ( 12.4 mm ). Body oval to rounded, 1.3– 1.5 times as long as greatest width, lateral margins slightly convex. Colour light to dark grey in live specimens and dark brown to tan in ethanol preserved specimens, with occasional chromatophores on antennae, pereopods, mouthparts, pleon and pereon. Cephalon 4 times longer than wide, triangular, anterior margin rounded to form blunt rostrum. Eyes oval, with distinct margins, about 0.2 times width of head. Pereonite 1 with rounded antero-lateral sides and angles, most narrow pereonite. Pereonite 2 shortest with rounded convex lateral margins, pereonites 2–4 increasing in width and length to a maximum length at pereonite 3 and 4, and maximum width at pereonite 4. Pereonites 5–7 decreasing in width and length, becoming progressively more rounded posteriorly and concave around the pleon. Coxae of pereonites 3–7 rounded and visible in dorsal view. Pleon . Pleonite 1 most narrow, posterior margin concave. Pleonites laterally acute. Pleotelson 1.4 times as wide as long, widest anteriorly, lateral margins convex, smooth, posterior margin evenly rounded without median point. Antennule extending to middle of eye, composed of 7 articles, slightly stouter than antenna, article 1 widest (as long as wide) and others decreasing in width progressively; articles 1 and 2 with pectinate scales. Variability in short simple setae on all articles with one plumose seta on article 4 and article 7 terminating in 5–7 short simple setae. Antenna extending to posterior margin of cephalon, composed of 10 articles progressively decreasing in width. Antenna peduncle article 4 1.5 times as long as wide, 1.2 times as long as article 3, inferior margin with 1 plumose seta; clusters of 4–8 short simple setae on articles 6–8, article 9 terminating in 6–10 short simple setae. Labrum simple, crescent shaped. Mandible process with pectinate scales and ending in sharp spine and 2 simple setae, palp article 2 with 6 distolateral serrate setae, palp article 3 with 10 short and 4 long serrate setae on distal margin. Maxillule simple with 4 terminal, robust setae. Maxilla mesial lobe partly fused to lateral lobe, with 2 large recurved robust setae and 2 simple setae; lateral lobe with 2 simple setae and 7 recurved robust setae; both lobes covered in pectinate scales. Maxilliped of ovigerous female composed of three palp articles; article 1 covered in pectinate scales, weakly segmented with lamellar oostegite lobe and second, smaller oostegite lobe on basal part of article. Oostegite lobe margins covered in numerous plumose setae; article 2 with 2 small simple setae; article 3 with 3 recurved robust setae and 2 simple setae. Pereopods similar and gradually increasing in size towards posterior, all without robust or simple setae. Pereopod 1 basis 1.5 times as long as greatest width, ischium 1.5 times as long as wide, merus proximal margin with bulbous protrusion, carpus with rounded proximal margin, propodus 1.2 times as long as wide, dactylus slender, 3.0 times as long as basal width. Pereopods 2–3 similar to pereopod 1. Pereopods 4–7 rectangular basis, without connective tissue on ischium and bulbous protrusion on merus. Pereopod 7 basis 1.53 times as long as greatest width, ischium 1.5 times as long as wide, merus proximal margin with slight bulbous protrusion, carpus with slight bulbous protrusion, propodus a little less than twice (1.95) as long as wide, dactylus slender, 2.4 times as long as basal width. Oostegites attach to pereopods 2–5. Pleopods simple, not visible in dorsal view; peduncles without retinaculae, no setae present, slight depression on central dorsal surface of each pleopod rami. Pleopod 1 exopod 1.2 times as wide as long, distally broadly rounded, lateral margin weakly convex, mesial margin weakly produced, endopod 1.2 times as wide as long, lateral margin straight, mesial margin slightly convex, smaller than exopod. Pleopods 2–5 similar to pleopod 1 but with the mesial margins becoming more strongly produced; pleopods 3–5 endopod proximal borders extending below exopod to peduncle. Uropod more than half length of pleotelson, peduncle 1.2 times longer than rami, without setae. Endopod lateral margin convex, apex slightly pointed, with 6–8 small plumose setae. Exopod wider and slightly longer than endopod, 2.7 times as long as greatest width, lateral and mesial margins weakly convex, apex rounded, without setae. Male . Length 9.0– 18.5 mm ( 12.9 mm ), width 4–8 mm ( 5.3 mm ). Males similar to females but much smaller. Body less round than females, rectangular, 1.7–1.8 times as long as wide. Antennae with more setae present. Cephalon not immersed in pereonite 1. Pereopod 1 with antero-lateral sides and angles more rectangular. Pleopod 2 longer than in female, with appendix masculina. More robust setae on uropods. Variation of female. Antenna highly variable, frequently malformed; ranging from 5 to 9 articles. Maxilla with 5–8 robust setae on one lobe. Pleotelson ratio 1.3 times as long as wide. Exopod reduced and endopod occasionally absent. Remarks. As mentioned earlier, Cinusa is a monotypic genus occurring in only one species of fish, namely Amblyrhynchotes honckenii . This host fish obtains a maximum size of 30 cm TL and occurs in the Indo-West Pacific from South Africa to China as well as the Marshall Islands in Micronesia . This species seems to be extremely host specific which is uncommon for South African cymothoids. The original description of Cinusa tetrodontis by Schioedte and Meinert (1884) stated that C. tetrodontis adult females are usually between 18–26 mm in length, have a deeply grooved head and pleotelson, and the first pleonite is hidden. It also mentioned that the male and female differ with the males having ‘styliform processes of the second branchial leg produced and bearing longitudinal lamellae’. None of these characteristics were seen in the material examined, however, all the other information concurs with that observed in the material used for the present study.