Cassagnaua, Ozdikmen, 2009

Remarks on nomenclatural change

The genus Cassagnaua Özdikmen, 2009 was proposed as a substitute name for Pectinura Cassagnau, 1983 by Özdikmen (2009) and presently comprises only one species, Cassagnaua hongkongensis ( Yosii, 1976) , which was previously transferred from Womersleya Denis, 1948 by Cassagnau (1983). In this study, we transfer another species originally described under Womersleya to this genus, for which we propose the name Cassagnaua formosana ( Lee & Kim, 1990) comb. nov.

The diagnostic characters of Womersleya , which is currently placed within the tribe Neanurini ( Smolis & Paśnik 2020) , include fusion of the Di and De tubercles on the head and fusion of the Di, De and Dl tubercles on Abd. V ( Deharveng 1988). The type species, Womersleya vicina ( Denis, 1934) , has 2+2 unpigmented eyes. These characteristics, along with the importance of eye number in Neanuridae taxonomy, as emphasised by Jiang & Wang (2024), exclude the 3-eyed species C. formosana comb. nov. from Womersleya .

The attribution of C. formosana comb. nov. to the genus Cassagnaua requires an expansion of its definition, to include both species with dorsal tubercles on Abd. V, which are shifted laterally towards the Abd. VI in C. hongkongensis , or with tubercles in the normal position as in C. formosana comb. nov. In the original definition of Cassagnaua , the eyes were described as pigmented ( Cassagnau 1983); however, the presence or absence of eye pigmentation in C. formosana comb. nov. was not specified in the original description by Lee & Kim (1990). The updated diagnosis of Cassagnaua is as follows:

Diagnosis. Eyes 3+3. Hypodermal blue pigment absent. Maxillae styliform; mandibles elongated into a comblike shape, with a large basal tooth and 12–25 small teeth. Di and De tubercles on the head either well-defined and separated or reduced. Di tubercles separated from other dorsal tubercles on Abd. V. Dorsal tubercles on Abd. V either in their normal position or shifted laterally towards Abd. VI.

Womersleya marhia Baijal, 1958 , originally described from India, is also likely to be transferred to Cassagnaua due to its possession of 3+3 eyes. However, as the status of some relevant characteristics of this species, like the morphology of the tubercles on the head and Abd. V, remain unclear, W. marhia is tentatively retained within Womersleya at this time.

Based on our notes, Cassagnaua includes the species listed in the identification key below, which possess sensory chaetae on the L tubercles of Abd. IV. Their well-developed mandibles and the presence of sensory chaetae on the L tubercles of Abd. IV suggest close affinity with one of the groups within Crossodonthina , which are characterised by having 3+3 eyes and sensory chaetae on the L tubercles of Abd. IV.

Identification key to the species of Cassagnaua View in CoL

1 Cephalic O chaeta absent. Dorsal tubercles on Abd. V shifted laterally towards the Abd. VI............................................................................................... C. hongkongensis ( Yosii, 1976) ( China)

- Cephalic O chaeta present. Tubercles on Abd. V in the normal position, not shifted laterally towards the Abd. VI................................................................. C. formosana ( Lee & Kim, 1990) comb. nov. (Taiwan)