Retrodesmus dammermani Chamberlin, 1945

Golovatch, Sergei I., Geoffroy, Jean-Jacques, Stoev, Pavel & Spiegel, Didier Vanden, 2013, Review of the millipede family Opisotretidae (Diplopoda, Polydesmida), with descriptions of new species, ZooKeys 302, pp. 13-77 : 30-33

Retrodesmus dammermani Chamberlin, 1945 Figs 12, 13

Retrodesmus dammermani Holotype ♂ (AMNH), Java, Tjibodas, 1400 m, Aug. 1921, Dammerman [on label].

Descriptive notes and remarks.

The series also contains a microvial with several fragments of a presumed ♀ labeled "♀ allotype", but, having not been mentioned in the original description ( Chamberlin 1945), this ♀ cannot be considered as part of the type series.

The holotype, an intact ♂, has been restudied, with several colour pictures taken to show the habitus (Fig. 12), and line drawings executed of a midbody paratergite and the gonopods in situ (Fig. 13).

Chamberlin’s (1945) succinct description is basically correct in showing quite broad and mostly slightly upturned paraterga with 2 or 3 minute, lateral, setiferous incisions; the caudal corners of postcollum paraterga until the 17th are produced increasingly well behind the rear tergal margin, roundly dentiform; the metaterga support three rather regular, transverse rows of short to medium-sized bacilliform setae; the ozopores are located rather close to the lateral margin of ozoporiferous paraterga, but quite far from the caudal corner (Fig. 13A). Body length ca 6 mm, width 0.55 mm.

The gonopods (Fig. 13B), contrary to Chamberlin’s (1945) sketch (his fig. 20), show only a slightly curved telopodite devoid of a drastic parabasal geniculation. The coxae bear several setae on the ventral side. The telopodite is rather stout, unipartite, slightly hollow on the caudal face, only subterminally subdivided into a frontal stump (s) beset with bacilliform ornamentations and surmounted by a long spine (sp), and a simple, similarly spinigerous branch (b). The seminal groove runs along the caudal face to flush open on the surface, with neither a solenomere nor an accessory seminal chamber, nor a hairy pulvillus, terminating near the base of both s and b.

As Hoffman (2005, p. 75) once put it quite sarcastically as regards the quality of Chamberlin’s (1945) paper, "There is no evidence that Professor Chamberlin invested much time in consultation of available literature sources". Nevertheless, his Retrodesmus remains a valid genus sufficiently distinct from the other opisotretid genera.

In addition to the type species, Retrodesmus also includes Retrodesmus cavernicola sp. n., a presumed troglobite from Papua New Guinea.