Citation: Hadfield KA, Bruce NL, Smit NJ (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: 1–42. doi: 10.3897/zookeys.400.6878
The genus Ceratothoa Dana, 1852 is revised for South African waters and re-diagnosed. Ceratothoa retusa (Schioedte & Meinert, 1883) is recorded from the eastern coast, and Ceratothoa africanae sp. n. and C. famosa sp. n. are described; C. imbricata (Fabricius, 1775) and C. trigonocephala (Leach, 1818), are redescribed, revised and excluded from the South African fauna. Ceratothoa africanae sp. n. can be distinguished by the stout body shape of the female; triangular cephalon with a pointed rostrum; short uropods which do not extend past the pleotelson; large carinae on the pereopod basis; a broad pleon; and large medial lobes on female pleopods. Ceratothoa famosa sp. n. is characterised by the long rectangular body shape; pereonite 1 with a raised medial protrusion; narrow antenna with antennule article 1 expanded; uropods which reach the posterior margin of the pleotelson; narrow rami on uropods; and no appendix masculina on pleopod 2 of the male specimens.
Isopod, cymothoid, buccal-cavity, fish parasite, tongue-biter, Indian Ocean
Cymothoid isopods are obligate parasites of both freshwater and marine fishes, where they will attach to the external surfaces, gills or inside the buccal-cavity of their fish host (
Very little is known about the cymothoid isopods from southern Africa and the western Indian Ocean (
Ceratothoa has long been considered to have three species in South Africa: Ceratothoa imbricata (Fabricius, 1775), Ceratothoa retusa (Schioedte & Meinert, 1883) and Ceratothoa trigonocephala (Leach, 1818) (see
Type material for Ceratothoa imbricata and Ceratothoa trigonocephala were borrowed from the Natural History Museum, UK. All available material from Iziko South African Museum labelled as a Ceratothoa species was borrowed with additional specimens being obtained from fish hosts held in the South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, South Africa.
New material was collected along the south coast of South Africa by the FRS Africana and from intertidal rock pools at Tsitsikamma National Park.
Isopods were processed according to the techniques described in
Host nomenclature and distribution are from FishBase (
Synonymies: Those records that we have been unable to confirm directly from specimens or the published figures, or that we otherwise have reasonable doubts about, have been removed from the synonymy.
Abbreviations. BMNH—British Museum, Natural History, UK (now NHMUK); MNHN—Muséum National d’Histoire Naturelle, Paris; NHMUK—Natural History Museum, UK; SAIAB—South African Institute for Aquatic Biodiversity, Grahamstown; SAM—South African Museum, Cape Town; SMNH—Swedish Museum of Natural History, Stockholm; ZMUC—Zoological Museum, University of Copenhagen; TL—total length; W—width.
http://species-id.net/wiki/Ceratothoa
Body narrow, strongly vaulted, 2.1–2.9 times as long as wide, widest at pereonite 5. Cephalon triangular, with blunt rostrum, anterior margin ventrally directed, posterior margin straight. Antennular bases in contact, broad and expanded, subequal to antenna. Eyes distinct. Mandible not expanded; mandible palp article 2 longer than article 3. Maxilla medial lobe partly fused, prominent nodulose spines on each lobe. Maxillule with 4 terminal spines. Maxilliped article 3 with 2 recurved spines, with oostegite lobe. Pereonite 1 anterolateral angles extensions encompassing cephalon. Pereonites 6 and 7 posterolateral margins not produced. Pereonite 7 extends past pleonite 1. Pleon subequal or narrower than pereon. Pleonite 1 width narrower than other pleonites, pleonites 2–5 subequal in width. Pleotelson narrower than pleonites. Coxae 5–7 visible, reniform, often produced and rounded, shorter than somite. Brood pouch from coxae 1–4 and 6, posterior pocket absent. Pereopods 5–7 basis with large blade-like carina, without robust setae. Pereopod 7 slightly larger or more than 1.5 times longer than pereopod 1. Pleopods from dorsal view not visible, decreasing in size posteriorly. Pleopods 1–5 with small pleats or pockets, with proximomedial lamellar lobe (more pronounced in pleopods 3–5), peduncle lobes on the lateral margin absent. Uropod rami short, not extending past posterior margin of pleotelson, subequal.
Ceratothoa can best be identified by the triangular cephalon, contiguous antennular bases, pleonite 1 narrower than the other pleonites, elongate body (2.1–2.9 times as long as wide), and subequal uropod rami which extend to the posterior margin of the pleotelson.
The most recent reviews of this genus are those of
Phylogenetic relationships of the cymothoid genera remain unassessed, other than comments given by
In a preliminary phylogenetic analysis using 23 cymothoid genera, with Rocinela Leach, 1818 (Aegidae) as the outgroup (
Ceratothoa is most closely related to Glossobius and this was shown in the preliminary study where the two genera grouped as sister taxa (
http://species-id.net/wiki/Ceratothoa_retusa
Indian Ocean—records from Mozambique, South Africa, Red Sea, India, Indonesia and northern Australia (see
Hemirhamphidae buccal-cavity—Hemirhamphus far (Forsskål, 1775) and Hemirhamphus robustus Günther, 1866 (see
Ceratothoa retusa can be identified by the large pereonite 1 with an anterolateral ridge and small cephalon sunken into pereonite 1. Pereonite 1 is deeply concave with anterolateral margins which almost extend to the tip of the cephalon. The pleotelson is broader than long and the uropods extend past the pleotelson margin (
http://zoobank.org/B4BA5F68-2070-4464-88FB-B27356761920
http://species-id.net/wiki/Ceratothoa_africanae
Figs 1–7, 21Holotype. 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).
Ceratothoa africanae sp. n. female holotype (29 mm) (SAM A45937): A dorsal view B antero-dorsal view of pereonite 1 and cephalon C ventral view of cephalon D dorsal view of pleotelson E lateral view.
Ceratothoa africanae sp. n. female paratype (30 mm) (SAM A45938): A antennule B antenna C mandible D tip of maxillule E maxillule F tip of maxilliped article 3 G maxilla H tip of maxilla I maxilliped with oostegite J oostegites K uropod.
Ceratothoa africanae sp. n. female holotype (29 mm) (SAM A45937): A pereopod 1 B pereopod 2 C pereopod 6 D pereopod 7.
Ceratothoa africanae sp. n. female paratype (30 mm) (SAM A45938): 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.
Ceratothoa africanae sp. n. male paratype (14 mm) (SAM A45938): A dorsal view B antero-dorsal view of pereonite 1 and cephalon C ventral view of cephalon D dorsal view of pleotelson E lateral view.
Ceratothoa africanae sp. n. male paratype (14 mm) (SAM A45938): A antennule B antenna C maxillule D mandible E maxilla F tip of maxilliped G maxilliped H uropod I pereopod 1 J pereopod 7.
Ceratothoa africanae sp. n. male paratype (14 mm) (SAM A45938): 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.
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.
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.
Named for FRS Africana, from which the species was collected, also acknowledging that this is the first Ceratothoa species to be described from Africa.
Eastern Cape Province, South Africa: from Tsitsikamma to Algoa Bay.
Found in the buccal-cavity, on the tongue of Spondyliosoma emarginatum (Valenciennes, 1830).
9/17 (53%) of Spondyliosoma emarginatum infected from the FRS Africana trawls, 4/68 (5.9%) from the SAIAB collections.
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.
http://zoobank.org/6F47F60D-9157-446F-9A2E-8A189549F087
http://species-id.net/wiki/Ceratothoa_famosa
Figs 8–14, 21Holotype. Female (23 mm TL; 10 mm W), collected from Tsitsikamma National Park (34°1'S, 23°52'E) along the south coast of South Africa from the buccal-cavity of Diplodus sargus capensis, March 2005, coll. K.A. Hadfield (SAM A45939).
Paratypes. All from Tsitsikamma National Park (34°1'S, 23°52'E), Western Cape Province. From the buccal-cavity of Diplodus sargus capensis: dissected female (27 mm TL; 12 mm W), dissected male (13 mm TL; 6 mm W), April 2009, coll. K.A. Hadfield (SAM A45940); female (17 mm TL; 7 mm W), males (7, 14 mm TL; 3, 6 mm W), March 2005, coll. K.A. Hadfield (SAM A45941).
From the buccal-cavity of Sparadon durbanensis: female (15 mm TL; 6 W), male (5.5 mm TL; 2 mm W), April 2009, coll. K.A. Hadfield (SAM A45942).
Other material. In the possession of authors at NWU. From Diplodus sargus capensis: Cape Agulhas (34°49'S, 20°0'E): female (18 mm TL; 7 mm W), male (9 mm TL; 3 mm W). Kenton-on-sea (33°42'S, 26°41'E): female (14 mm TL; 5 mm W), male (5 mm TL; 2 mm W), May 1974. Morgan Bay (32°42'S, 28°20'E): two females (10, 12 mm TL; 3, 4 mm W), April 2003. Swartkops River Estuary (33°52'S, 25°38'E): female (10 mm TL; 3 mm W), male (6 mm TL; 2 mm W), July 1980. Transkei, between Goss Bay and Lupatana: female (10 mm TL; 4 mm W), September 1975. Transkei, Grosvenor Point (31°22'S, 29°53'E): female (15 mm TL; 6 mm W), male (6 mm TL; 2 mm W), September 1975. Tshani (31°56'S, 29°12'E): female (10 mm TL; 3 mm W), June 1996.
From Diplodus cervinus hottentotus: Kleinemonde (33°32'S, 27°03'E): female (25 mm TL; 6 mm W), male (5 mm TL; 2 mm W), June 1975; female (15 mm TL; 6 mm W), male (6 mm TL; 2 mm W), March 1975; Keiskamma River Mouth (33°16'S, 27°29'E): female (18 mm TL; 8 mm W), male (9 mm TL; 4 mm W), February 1976; Knysna (34°5'S, 23°3'E): female (19 mm TL; 7 mm W), male (8 mm TL; 3 mm W), 1945–1969. Tsitsikamma National Park (34°1'S, 23°52'E): female (20 mm TL; 7 W), male (14 mm TL; 5 mm W), 17 juveniles, March 2007.
From Sparadon durbanensis: Cape Padrone, Eastern Cape (33°46'S, 26°28'E): four pullus (5 mm TL; 2 mm W), July 1975. Kleinemonde (33°32'S, 27°03'E): five pullus (4 mm TL; 2 mm W), February 1977. Knysna (34°5'S, 23°3'E): two pullus (5 mm TL; 2 mm W), 1945–1965. Tsitsikamma National Park (34°1'S, 23°52'E): female (26 mm TL; 12 W), male (12 mm TL; 5 mm W), 35 juveniles, July 2008.
Ceratothoa famosa sp. n. female holotype (28 mm) (SAM A45939): A dorsal view B anterior view of pereonite 1 and cephalon C ventral view of cephalon D dorsal view of pleotelson E lateral view.
Ceratothoa famosa sp. n. female paratype (26 mm) (SAM A45941): A antennule B antenna C mandible D tip of maxillule E maxillule F tip of maxilla G tip of maxilliped article 3 H maxilla I maxilliped with oostegite J oostegites K uropod.
Ceratothoa famosa sp. n. female holotype (28 mm) (SAM A45939): A pereopod 1 B pereopod 2 C pereopod 6 D pereopod 7.
Ceratothoa famosa sp. n. female paratype (26 mm) (SAM A45941): 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.
Ceratothoa famosa sp. n. male paratype (12 mm) (SAM A45941): A dorsal view B anterior view of pereonite 1 and cephalon C ventral view of cephalon D dorsal view of pleotelson E lateral view.
Ceratothoa famosa sp. n. male paratype (12 mm) (SAM A45941): A antennule B antenna C maxillule D mandible E maxilla F maxilliped G uropod H pereopod 1 I pereopod 7.
Ceratothoa famosa sp. n. male paratype (12 mm) (SAM A45941): 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.
Length 10–28 (16.9) mm, width 3–12 (6.0) mm.
Body rectangular, 1.7 times as long as greatest width, dorsal surfaces smooth and polished in appearance, widest at pereonite 4 and pereonite 5, most narrow at pereonite 7, lateral margins slightly convex. Cephalon 0.8 times longer than wide, slightly visible in dorsal view, triangular. Frontal margin rounded to form blunt rostrum. Eyes irregular in outline. Pereonite 1 with median projection, anterior border straight, anterolateral angle with distinct anterior projection, posterior margins of pereonites smooth and slightly curved laterally. Coxae 2–3 with posteroventral angles not visible; 4–7 rounded. Pereonites 1–5 increasing in length and width; 6–7 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 and medial indent. Pleotelson 0.5 times as long as anterior width, dorsal surface smooth, lateral margins posteriorly narrow, posterior margin broadly truncate, without median point.
Antennule more stout than antenna, comprised of 7 articles; peduncle articles 1 and 2 distinct and articulated; article 2 0.8 times as long as article 1; article 3 0.3 times as long as combined lengths of articles 1 and 2, 0.8 times as long as wide; flagellum with 4 articles, extending to anterior of pereonite 1. Antenna comprised of 9 articles. Antenna peduncle article 3 1.4 times as long as article 2, 1.1 times as long as wide; article 4 1.1 times as long as wide, 0.9 times as long as article 3; article 5 0.5 times as long as article 4, 0.8 times as long as wide. Antenna flagellum with 4 articles, last article terminating in no setae, extending to anterior margin of pereonite 1. Anterior margin rounded, forming median point. Mandibular process ending in an acute incisor, with no simple setae, mandible palp article 2 with no distolateral setae, and article 3 with 7 serrate setae. Maxillule simple with 4 terminal robust setae. Maxilla mesial lobe partly fused to lateral lobe; lateral lobe with no simple setae, 6 recurved robust setae; mesial lobe with no simple setae, and 4 large recurved robust setae. Maxilliped weakly segmented, with lamellar oostegite lobe, palp article 2 with no simple setae, article 3 with 3 recurved robust setae, and no simple 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 0.8 times as long as basis; merus proximal margin with bulbous protrusion; carpus with straight proximal margin; propodus 1.4 times as long as wide; dactylus slender, 1.1 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. Pereopods gradually increasing in size towards posterior and all without robust or simple setae. Pereopod 6 basis 1.6 times as long as greatest width, ischium 0.8 times as long as basis, propodus 1.5 as long as wide, dactylus 1.2 as long as propodus. Pereopod 7 basis 1.3 times as long as greatest width; ischium 0.9 as long as basis, without protrusions; merus proximal margin with slight bulbous protrusion, merus 0.3 as long as ischium, 0.5 times as long as wide; carpus 1 as long as ischium, without bulbous protrusion, 0.7 times as long as wide; propodus 2.1 as long as ischium, 1.4 times as long as wide; dactylus slender, 1.3 as long as propodus, 2.9 times as long as basal width.
Pleopods without setae, exopod larger than endopod. Pleopod 1 exopod 1.1 times as long as wide, lateral margin weakly convex, distally broadly rounded, mesial margin straight; endopod 1.4 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. Pleopods 3–5 endopods proximal borders do not extend below exopod to peduncle. Large medial lobes absent.
Uropod same length as pleotelson, peduncle 1 times longer than rami, peduncle lateral margin without setae; rami extending to pleotelson apex, marginal setae absent, apices narrowly rounded. Endopod apically slightly pointed, 4.1 times as long as greatest width, lateral margin straight, terminating without setae, mesial margin straight. Exopod extending to end of endopod, 3.3 times as long as greatest width, apically rounded, lateral margin weakly convex, terminating with no setae, mesial margin straight.
Length 4–14 (8.2) mm, width 1–5 (3.3) mm.
Males similar to females but much smaller. Body rectangular, 1.6 times as long as wide. Penis small, low tubercles. Pleopod 2 appendix masculina absent.
A photograph by one of us (NJS) of this species in the mouth of a Diplodus sargus capensis from Tsitsikamma National park, posted on the internet in 2004 has been used in many media reports worldwide, including magazines, children’s books, documentaries, nature programmes, daily news reports, and even in a motion picture. The epithet is derived from famosus (Latin—famous) (
Known from off the southern coast of South Africa: Cape Agulhas; Knysna; Tsitsikamma; Swartkops River Estuary; Kenton-on-sea; Kleinemonde; Keiskamma River Mouth; Morgan Bay; Tshani; Grosvenor Point; and Transkei (between Goss Bay and Lupatana).
Found on the tongue of Diplodus sargus capensis (Smith, 1844), Diplodus cervinus hottentotus (Smith, 1844) and Sparadon durbanensis (Castelnau, 1861).
1/3 (33.3%) of Diplodus cervinus hottentotus, 6/20 (30%) of Diplodus sargus capensis and 6/33 (18.2%) of Sparadon durbanensis infected from Tsitsikamma National Park; 26/366 (7.1%) of Diplodus cervinus hottentotus, 78/1004 (7.8%) of Diplodus sargus capensis and 11/100 (11%) of Sparadon durbanensis from the SAIAB collections.
Ceratothoa famosa sp. n. can be distinguished by the long rectangular body shape, pereonite 1 with a raised medial protrusion, a blunt rostrum, narrow antenna with antennule article 1 expanded, uropods which reach the posterior margin of the pleotelson, pereopods 1 and 2 with large bulbous protrusion on merus, narrow rami on uropods, and no appendix masculina on pleopod 2 of the male specimens.
Ceratothoa famosa sp. n. is similar to Ceratothoa trigonocephala in having pereonites 1–4 almost subequal but has a more bluntly rounded anterior margin of the cephalon observed in Ceratothoa imbricata as well as the two mediolateral concave indents in pleonite 5. Specific characters for Ceratothoa famosa include an antennule with an enlarged first article; a medial protrusion on pereonite 1 creating a rounded elevation around the cephalon; and a rostral point which is folded over between the antennae. The anterolateral margins are close to the cephalon and are bluntly rounded extending just past the middle of the cephalon. The uropods are the same length as the pleotelson and the male specimens lack an appendix masculina on pleopod 2 as seen with Ceratothoa oestroides (Risso, 1826), Ceratothoa italica Schioedte & Meinert, 1883, Ceratothoa capri (Trilles, 1964c), Ceratothoa gilberti (Richardson, 1904) and Cymothoa gaudichaudii. The pleopods do not have many folds or lobes but the pereopods have large carinae and extended protrusions on the merus of pereopods 1 and 2.
Other differences between Ceratothoa famosa sp. n. and Ceratothoa africanae sp. n. is the rostral point, which is blunt and ventrally directed and does not fold over in Ceratothoa africanae.; Ceratothoa famosa pereonite 7 overlaps pleonite 1 and the P1–P4 merus has a large bulbous protrusion which is smaller in P5–P7 (opposite in Ceratothoa africanae sp. n.); and Ceratothoa famosa. has pointed rather than rounded anterolateral margins on pereonite 1 as seen in Ceratothoa africanae.
Two widely recorded species Ceratothoa imbricata (Fabricius, 1775) and Ceratothoa trigonocephala (Leach, 1818), both of which have long been considered to occur in South Africa (see
http://species-id.net/wiki/Ceratothoa_imbricata
Figs 15–18, 21Holotype of Ceratothoa imbricata. The Natural History Museum, London (BMNH 1979.403.1) – female (34 mm TL; 16 mm W) collection of Sir Joseph Banks, Linnean Society, from New Zealand, coll. S.W.J. Banks, host unknown (
Holotype of Ceratothoa banksii. The Natural History Museum, London (BMNH 1979.402.1) – female (37 mm TL; 18 mm W), presented by Leach to the Museum of the Linnean Society, from New Zealand, White’s MS Cat No. 222, Coll. W.E. Leach, host unknown.
Body ovoid, 2.1 times as long as greatest width, dorsal surfaces slightly bumpy, widest at pereonite 5, most narrow at pereonite 1, lateral margins posteriorly ovate. Cephalon 0.7 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 distinct produced point extending to or beyond the eye margin, posterior margins of pereonites smooth and slightly curved laterally. Pereonites 1–5 increasing in length and width; 6–7 decreasing in length and width; 6 and 7 narrower. Pleon with pleonite 1 most narrow, 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 produced medially. Pleotelson 2 times as long as anterior width, dorsal surface with lateral indent, lateral margins weakly convex, posterior margin rounded, without median point. Antennule more stout than antenna, comprised of 8 articles. Antenna comprised of 4 articles. Pereopod 1 basis 1.5 times as long as greatest width; ischium 0.8 times as long as basis; merus proximal margin with bulbous protrusion; carpus with straight proximal margin; propodus 1.5 times as long as wide; dactylus slender, 0.9 as long as propodus, 2.3 times as long as basal width. Pereopod 2 propodus 1.3 as long as wide; dactylus 0.6 as long as propodus. Pereopods 3 similar to pereopod 2. Pereopod 6 basis 1.4 times as long as greatest width, ischium 0.7 times as long as basis, propodus 1.5 as long as wide, dactylus 1 as long as propodus. Pereopod 7 basis 1.2 times as long as greatest width; ischium 0.7 as long as basis, without protrusions; merus proximal margin with slight bulbous protrusion, merus 0.4 as long as ischium, 0.6 times as long as wide; carpus 0.6 as long as ischium, without bulbous protrusion, 0.5 times as long as wide; propodus 0.6 as long as ischium, 1.4 times as long as wide; dactylus slender, 1.1 as long as propodus, 2.5 times as long as basal width. Uropod longer than the pleotelson, peduncle 0.7 times longer than rami, peduncle lateral margin without setae; rami extending beyond pleotelson, marginal setae absent, apices narrowly rounded.
Ceratothoa imbricata (Fabricius, 1775), female holotype (34 mm) (BMNH 1979.403.1): A dorsal view B antero-dorsal view of pereonite 1 and cephalon C dorsal view of pleotelson D lateral view.
Ceratothoa imbricata (Fabricius, 1775), female holotype (34 mm) (BMNH 1979.403.1): A pereopod 1 B pereopod 2 C pereopod 6 D pereopod 7.
Ceratothoa imbricata (Fabricius, 1775), female (37 mm), (BMNH 1979.402.1 originally designated as holotype of Ceratothoa banksii Leach, 1818): A dorsal view B antero-dorsal view of pereonite 1 and cephalon C ventral view of cephalon D dorsal view of pleotelson E lateral view.
Ceratothoa imbricata (Fabricius, 1775), female (37 mm), (BMNH 1979.402.1 originally designated as holotype of Ceratothoa banksii Leach, 1818): A pereopod 1 B pereopod 2 C pereopod 6 D pereopod 7.
Australia (
From the mouth of a salmon–trout; from a Monacanthus sp. (
Ceratothoa imbricata can be identified by a large pereonite 1 with anterolateral margins extending past the eyes; uropods as long or longer than the pleotelson margin; merus with bulbous protrusion; a blunt rostrum; and body widest at pereonite 5.
It is apparent that over the years there have been many misidentifications of Ceratothoa imbricata, Ceratothoa banksii and Ceratothoa trigonocephala, with these names being widely misapplied. The description of Ceratothoa banksii from New Zealand, given by
No South African specimens were found, fresh or from museum collections, that could be identified as Ceratothoa imbricata, and the species is here excluded from the South Africa fauna.
http://species-id.net/wiki/Ceratothoa_trigonocephala
Figs 19–21Lectotype [here designated]: The Natural History Museum, London (NHMUK 2013.1013) – female specimen (42 mm TL) collected by W.E. Leach, White’s MS Cat no. 404 a, b, host and locality unknown. Also noted: the female drawn was very squashed and missing pereonite 1.
Paralectotype. The Natural History Museum, London (BMNH 1979.404.2) – female specimen (17 mm TL without cephalon) collected by W.E. Leach, White’s MS Cat no. 404 a, b, host and locality unknown. Also noted: damaged female, missing the cephalon and oostegites, with dissected uropods.
Body margins sub-parallel, 2.4 times as long as greatest width, dorsal surfaces smooth and polished in appearance, widest at pereonite 5 and pereonite 6, most narrow at pereonite 1, lateral margins subparallel. Cephalon 0.6 times longer than wide, visible from dorsal view, triangular. Frontal margin rounded to form blunt rostrum. Eyes not visible. Pereonite 1 with slight indentations, anterior border slightly indented, anterolateral angle with distinct anterior projection, posterior margins of pereonites smooth and straight. Pereonites 1–5 increasing in length and width; 6–7 decreasing in length and width; 6 and 7 narrower. Pleon with pleonite 1 most narrow, visible in dorsal view; pleonites posterior margin smooth, mostly concave; posterolateral angles of pleonite 2 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 produced medially. Pleotelson 0.5 times as long as anterior width, dorsal surface with lateral indent, lateral margins weakly convex, posterior margin sub-truncate, without median point. Antennule more stout than antenna, comprised of 7 articles. Antenna comprised of 7 articles. Pereopod 1 basis 1.4 times as long as greatest width; ischium 0.8 times as long as basis; merus proximal margin without bulbous protrusion; carpus with rounded proximal margin; propodus 1.4 times as long as wide; dactylus slender, 1.2 as long as propodus, 2.3 times as long as basal width. Pereopod 2 propodus 1.4 as long as wide; dactylus 1.1 as long as propodus. Pereopods 3 similar to pereopod 2. Pereopod 6 basis 1.5 times as long as greatest width, ischium 0.8 times as long as basis, propodus 1.5 as long as wide, dactylus 1.1 as long as propodus. Pereopod 7 basis 1.4 times as long as greatest width; ischium 0.8 as long as basis, without protrusions; merus proximal margin with slight bulbous protrusion, merus 0.4 as long as ischium, 0.7 times as long as wide; carpus 0.3 as long as ischium, without bulbous protrusion, 0.7 times as long as wide; propodus 0.6 as long as ischium, 1.6 times as long as wide; dactylus slender, 1.2 as long as propodus, 2.5 times as long as basal width. 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.
Ceratothoa trigonocephala (Leach, 1818), female lectotype (42 mm) (NHMUK 2013.1013): A dorsal view B antero-dorsal view of pereonite 1 and cephalon C dorsal view of pleotelson D lateral view.
Ceratothoa trigonocephala (Leach, 1818), female lectotype (42 mm) (NHMUK 2013.1013): A pereopod 1 B pereopod 2 C pereopod 6 D pereopod 7.
Predominately the Indo-Pacific region: Australia; Vanuatu; and Indonesia (
There are currently no confirmed hosts for this species.
Ceratothoa trigonocephala has a triangular cephalon, for which it is named, and arched carinae on the last pair of pereopods. It is identified by the subequal pereonites 1–4; mid-dorsal protrusion on pereonite 1; short and bluntly rounded anterolateral margins of pereonite 1; and uropods which do not extend past the pleotelson posterior margin. The type locality and host for Ceratothoa trigonocephala were not mentioned in the original work by
Previously,
Ceratothoa trigonocephala has often been confused with Ceratothoa imbricata and a complete redescription and species clarification on these two species was needed. Differences between Ceratothoa imbricata and Ceratothoa trigonocephala, based on description of the type specimens include: Ceratothoa imbricata pereonite 1 is larger than pereonites 2–4 while in Ceratothoa trigonocephala these four pereonites are subequal; the posterior margin of pereonite 1 is curved in Ceratothoa imbricata and straight in Ceratothoa trigonocephala; Ceratothoa imbricata had a bulbous protrusion on the merus of pereopod 1 which is absent in Ceratothoa trigonocephala; and the uropods of Ceratothoa trigonocephala are shorter than the pleotelson but are longer in Ceratothoa imbricata. Furthermore, Ceratothoa imbricata has a more narrow and produced anterolateral angles on pereonite 1; a more rounded anterior margin on the cephalon; longer uropods which extend to or past the posterior margin of the pleotelson; and pereonite 1 is longer than pereonites 2–4 which are almost subequal in Ceratothoa trigonocephala.
Although this species had been recorded from South Africa (
Photographs of the Ceratothoa specimens studied: A lateral view of Ceratothoa africanae sp. n. (SAM A45938) B dorsal view of Ceratothoa africanae sp. n. (SAM A45938) C lateral view of Ceratothoa famosa sp. n. (SAM A45941) D dorsal view of Ceratothoa famosa sp. n. (SAM A45941) E dorsal view of Ceratothoa imbricata (Fabricius, 1775) (BMNH 1979.403.1) F dorsal view of Ceratothoa trigonocephala (Leach, 1818) (NHMUK 2013.1013).
We regard Ceratothoa imbricata and Ceratothoa trigonocephala as valid and distinct species despite the historical confusion over their respective identities. When comparing the holotype of Ceratothoa banksii to Ceratothoa imbricata, a number of similarities and differences could be seen but without other new material these differences seemed insufficient to remove the synonymy at present.
Records of Ceratothoa imbricata and Ceratothoa trigonocephala without figures or mention of museum material are impossible to verify. The synonymy presented here includes only those records that we can confirm against our redescription of the type material.
Although valid species, Ceratothoa imbricata and Ceratothoa trigonocephala do not occur in South Africa. These misidentifications were most probably referring to one of the two new species, Ceratothoa africanae sp. n. or Ceratothoa famosa sp. n.
The financial assistance of the National Research Foundation (NRF) towards this research is hereby acknowledged (project IFR2011040100022). Opinions expressed and conclusions arrived at, are those of the authors and are not necessarily to be attributed to the NRF. We thank the Captain and crew of the FRS Africana and Dr Sharon du Plessis (MCM Chief Scientist) for the opportunity to collect material during the April/May 2003 South Coast Hake Biomass Survey. Special thanks to the South African Institute for Aquatic Biodiversity (SAIAB) for allowing us to sample their fish collection and obtain valuable data on these isopods. Further thanks to Liz Hoenson from the Iziko South African Museum, Cape Town (SAM) and Miranda Lowe from the Natural History Museum, UK (NHMUK) for loan of the museum material used. NLB thanks the Museum of Tropical Queensland for permission to travel for this body of work.