Thordisa Bergh 1877
Creators: name: Valdés, Ángel
Publisher: name: Zenodo
Year: 2002
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Nudibranchia
Discodorididae
Thordisa

description: GENUS THORDISA BERGH, 1877   
 Thordisa Bergh, 1877a: 540. Type species: Thordisa maculigera Bergh, 1877, by subsequent designation by Bergh (1905).   
 Etidoris Ihering, 1886: 234. Type species: Etidoris ladislavii Ihering, 1886, by monotypy.   
 Nuvuca Marcus & Marcus, 1967a: 621. Type species: Nuvuca lurca Ev. Marcus & Er. Marcus, 1967, by original designation, syn. nov.   
 Pupsikus Marcus & Marcus, 1970a: 167–168. Type species: Pupsikus pinguis Er. Marcus & Ev. Marcus 1970, by original designation, syn. nov.   
 Diagnosis   
Dorsum covered with soft, elongate tubercles. Head with two conical oral tentacles. Anterior border of the foot grooved and notched. Labial cuticle smooth, lacking rodlets. Radula composed of simple, hamate teeth. Outermost lateral teeth multidenticulate. Reproductive system with a flattened, granular prostate, having two well differentiated regions. Penis armed or not with hooks. One or more accessory glands present, having one or more associated copulatory spines.  
 Remarks   
 Bergh (1877a) described the genus Thordisa based on Thordisa maculigera Bergh, 1877, but at the same time mentioned that Doris villosa Alder & Hancock, 1864, also belongs to this genus. According to Bergh (1877a) the main distinctive feature of this genus is the presence of elongate tubercles on the dorsum and pectinate outermost lateral teeth. Bergh (1891) regarded Etidoris Ihering, 1886 as a synonym of Thordisa. Bergh (1905) added the new species T. carinata Bergh, 1905, T. tristis, T. hilaris and with a question mark T. maculosa to the list of species of Thordisa, and designated T. maculigera as the type species.   
 The genus Nuvuca was described by Marcus & Marcus (1967a) on the basis of a single specimen of the new species Nuvuca lurca Ev. Marcus & Er. Marcus, 1967. According to these authors, the diagnostic features of this genus are: strongly spiculate body, unequal papillae on the dorsum, smooth labial cuticle, inner radular teeth with a short base and long cusp and pectinate outer teeth; a dart or copulatory spine joined to the male atrium; penis unarmed. Examination of the holotype of the type species revealed the presence of large dorsal papillae similar to those present in other species of Thordisa. The only remarkable difference between Nuvuca and Thoridisa is the absence of jaws in the former. This could be due to either interspecific variation or to Marcus & Marcus’s (1967a) neglecting to find this structure. Unfortunately, the parts of the foregut of the holotype dissected by Marcus & Marcus are not preserved with the rest of the specimen, and re-examination is not possible. Because the rest of the external and anatomical features of Nuvuca are identical to those of Thordisa, they are here regarded as synonyms.   
 Marcus & Marcus (1970a) described the genus Pupsikus based on the new species Pupsikus pinguis Ev. Marcus & Er. Marcus, 1970. According to these authors, Pupsikus is characterized by having a ridge connecting the tentacles with the foot, labial armature with rodlets and ‘a radula containing denticulate lateral and feathered marginal teeth’. The prostate is voluminous, the penis is armed with hooks and there is an accessory gland with a copulatory spine. The ridges that connect the oral tentacles and the foot in the single preserved specimen examined by Marcus & Marcus (1970a), are probably an artifact of observation. A re-examination of the holotype has revealed an oral morphology similar to that of other cryptobranch dorids. No trace of the ridge mentioned by Marcus & Marcus (1970a) has been found. The specimen was dissected and no anatomical information could be extracted from it, but the drawings and descriptions of Marcus & Marcus (1970a) are sufficient to identify it as a member of the genus Thordisa.
description: Published as part of Valdés, Ángel, 2002, A phylogenetic analysis and systematic revision of the cryptobranch dorids (Mollusca, Nudibranchia, Anthobranchia), pp. 535-636 in Zoological Journal of the Linnean Society 136 (4) on pages 571-574, DOI: 10.1046/j.1096-3642.2002.00039.x, http://zenodo.org/record/10114672