Ceratothoa collaris Schioedte & Meinert, 1883

Hadfield, Kerry A., Bruce, Niel L. & Smit, Nico J., 2016, Redescription of poorly known species of Ceratothoa Dana, 1852 (Crustacea, Isopoda, Cymothoidae), based on original type material, ZooKeys 592, pp. 39-91 : 47-51

Taxon classification Animalia Isopoda Cymothoidae

Ceratothoa collaris Schioedte & Meinert, 1883 Figure 4

Cymothoa oestroïdes.- Lucas 1849: 78, pl. 8, figs 4 a–c (see also page notes in Trilles 1972a p 1201). [not Ceratothoa oestroides (Risso, 1826)].

Ceratothoa collaris Schioedte & Meinert, 1883: 366-368, tab. XVI (Cym. XXIII) figs 8-9.- Carus 1885: 443.- Rokicki 1984a: 73; 1984b: 44-60, figs 9-12; 1985: 95-119, tabs. 1-3, fig. 8.- Trilles 1986: 623, tab. 1; 1994: 117.- Horton 2000: 1046-1047, figs 6 a–c.- Ramdane and Trilles 2008: 173-178.- Bariche and Trilles 2008: 85-93, figs 1-5.

Meinertia collaris forma typica .- Monod 1924a: 31-34; 1924b: 430-432.- Trilles and Raibaut 1973: 277-278.- Capapé and Pantoustier 1976: 203.

Meinertia collaris forma africana .- Monod 1924a: 31-34; 1924b: 430-432; 1925: 103-104.- Trilles 1977: 10.

Meinertia collaris forma globuligera .- Monod 1924a: 31-34; 1924b: 430-432.

Meinertia collaris .- Trilles 1972b: 1240-1241, pl. I (1-2).- Dollfus and Trilles 1976: 822.- Moreira and Sadowsky 1978: 100, 110, 113-114, 120, 134.

Ceratothoa collaris forma africana .- Trilles 1979: 515, 522.

Ceratothoa collaris forma typica .- Trilles 1979: 521.

Material examined.

Holotype. National Museum of Natural History, Paris (MNHN-Is386) - ovigerous female specimen (40 mm TL) collected in Algeria by Lucas ( Schioedte and Meinert 1883), host unknown, registered as Meinertia collaris , J.P. Trilles det. 17.12.1971 (n°40) ( Trilles 1972b). Also noted: both right antennae are missing and some appendages are broken.

Description.

Holotype female. Length 40 mm, width 18 mm.

Body oval, 1.8 times as long as greatest width, dorsal surfaces slightly bumpy, widest at pereonite 4 and pereonite 5, 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. Antennula more stout than antenna, shorter than antenna, with 7 articles. Antenna with 8 articles.

Pereonite 1 with slight indentations, anterior border straight, anterolateral angle with distinct anterior projection, extend to middle of the eye. Posterior margins of pereonites smooth and slightly curved laterally. Coxae 2-3 narrow; with posteroventral angles rounded; 4-7 acute, posteriorly pointed; not extending past pereonite margin. Pereonites 1-4 increasing in length and width; 5-7 decreasing in length and width; becoming more progressively rounded posteriorly. Pleon with pleonite 1 most narrow, visible in dorsal view; pleonites posterior margin smooth, mostly concave. Pleonite 2 not overlapped by pereonite 7; posterolateral angles of pleonite 2 narrowly rounded. Pleonites 3-5 similar in form to pleonite 2; pleonite 5 free, not overlapped by lateral margins of pleonite 4, posterior margin produced medially. Pleotelson 0.4 times as long as anterior width, dorsal surface with medial furrow, lateral margins weakly convex, posterior margin damaged and shallowly emarginate.

Pereopod 1 basis 1.7 times as long as greatest width; ischium 0.6 times as long as basis; merus proximal margin with bulbous protrusion; carpus with rounded proximal margin; propodus 1.6 times as long as wide; dactylus slender, 0.9 times as long as propodus, 2.1 times as long as basal width. Pereopod 7 basis 1.4 times as long as greatest width; ischium 0.8 times as long as basis, without protrusions; merus proximal margin with large bulbous protrusion, merus 0.4 times as long as wide, 0.3 times as long as ischium; carpus 0.4 times as long as wide, 0.2 times as long as ischium, without bulbous protrusion; propodus 0.9 times as long as wide, 0.4 times as long as ischium; dactylus slender, 1.5 times as long as propodus, 2.3 times as long as basal width.

Uropod more than half the length of pleotelson, peduncle 0.9 times longer than rami, peduncle lateral margin without setae; rami not extending beyond pleotelson, marginal setae absent, apices narrowly rounded. Endopod apically rounded, 3.6 times as long as greatest width. Exopod extending to end of endopod, 4 times as long as greatest width, apically rounded.

Size.

Female: 18-40 mm TL (9-18 mm W); male: 9-22 mm TL (4-10 mm W); second pullus: 2.7-2.8 mm TL (0.7-0.8 mm W) ( Monod 1924b, Capapé and Pantoustier 1976, Dollfus and Trilles 1976, Trilles 1977, 1979, Rokicki 1984a, b, Bariche and Trilles 2008).

Distribution.

Mediterranean and eastern Atlantic Ocean: Algeria ( Schioedte and Meinert 1883, Lucas 1849, Trilles 1972b, 1979, Ramdane and Trilles 2008); Morocco ( Monod 1924a, b, Trilles 1972b, Dollfus and Trilles 1976); Mauritania ( Monod 1924a, b, Trilles 1972b, 1977, Dollfus and Trilles 1976); Tunisia ( Trilles and Raibaut 1973, Capapé and Pantoustier 1976); Senegal ( Trilles 1979); and Lebanon ( Bariche and Trilles 2008).

Ceratothoa collaris is common in Tunisia ( Trilles and Raibaut 1973) and Mauritania ( Monod 1924a, Trilles 1977). This species has not been collected from the north or north-western Mediterranean countries despite many recent studies there. It has been found in southern areas of the Mediterranean, but never from Libya, Egypt, or Israel.

Hosts.

Frequently in the mouth of sparids from the genera Dentex and Pagellus (especially Dentex gibbosus and Pagellus erythrinus ): Dentex gibbosus (previously Dentex filosus ) (see Monod 1924a, b, Trilles 1972b, Trilles and Raibaut 1973, Rokicki 1984b), in Pagellus erythrinus (see Monod 1925, Bariche and Trilles 2008); mouth of Pagellus acarne (see Trilles 1972b, Dollfus and Trilles 1972); buccal cavity of Dentex dentex , Dentex maroccanus , Spicara sp., Smaris sp. and on ventral disc of Raja miraletus (see Trilles and Raibaut 1973); on Sargus sargus , Pagellus bogaraveo , pharynx of Pagellus erythrinus , and in gill cavity of a sparid (see Dollfus and Trilles 1972); on gill slits of Torpedo marmorata (see Capapé and Pantoustier 1976); in the mouth of Pseudotolithus moorii (previously Corvina camaronensis ) (see Trilles 1977); in the mouth of Smaris vulgaris and on gills of Pagellus sp. (see Trilles 1979); Dentex macrophthalmus , Pagrus pagrus (see Rokicki 1984b); in the branchial cavity of Pagrus caeruleostictus (see Ramdane and Trilles 2008, Bariche and Trilles 2008); less frequent on Dentex macrophthalmus , Pagellus acarne , Pagrus sp., and rarely on Dicentrarchus labrax and Epinephelus aeneus (see Bariche and Trilles 2008).

Lucas (1849) considered Ceratothoa collaris to have a low host specificity (euryxenic) but Bariche and Trilles (2008) showed that there is a clear preference for Sparidae fish, particularly Pagellus erythrinus , which is commonly parasitised in Lebanon and Africa (Morroco and Algeria). Monod (1925) also stated how most of these isopods recorded from Dentex filosus were actually removed from Pagellus erythrinus , especially in the case of Ceratothoa collaris forma africana .

Remarks.

Ceratothoa collaris can be distinguished by the prominent anterolateral projections which do not extend past the eyes and form a collar-like structure from where it gets its name. It also has a wide pleotelson (same width or wider than pleon), uropods that do not extend past the pleotelson and a large bulbous protrusion on the pereopod 7 merus.

Ceratothoa collaris was described from Algeria, originally misidentified as Ceratothoa oestroides by Lucas (1849). Later, Monod (1924a) described three different forms of this species, namely Ceratothoa collaris forma globuligera , Ceratothoa collaris forma africana and Ceratothoa collaris forma typica based on morphological differences of their cephlon and antennae ( Monod 1924a). Over the years, many researchers have identified other species where many forms are common, such as Ceratothoa steindachneri (see Horton 2000), but naming the different forms are not necessary, thus Bariche and Trilles (2008) removed the three Ceratothoa collaris forms.