Opisotretidae Hoffman, 1980

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 : 21

Family Opisotretidae Hoffman, 1980

Opisotretidae Hoffman, 1980: 176, 188.

Opisotretidae - Hoffman 1982: 722; Simonsen 1990: 53, 82.

Diagnosis.

A family of the suborder Polydesmidea with 19 (♂) or 20 (♂, ♀) segments. Body small to very small (3-16 mm long). Tegument microalveolate, limbus microspiculate. ♂ head with or without vertigial modifications. Antennae geniculate between segments 5 and 6, antennomeres 5 and 6 each with a compact group of bacilliform sensilla distodorsally. Metaterga with 2 or 3 regular, transverse rows of bacilliform, longitudinally ribbed setae sometimes borne on minute knobs; frontal margin of midbody paraterga only seldom forming clear-cut shoulders; side margin of paraterga often slightly incised, with 2 or 3 bacilliform setae. Pore formula normal, ozopores flush open dorsally, usually near to very near caudolateral corner of paraterga, only seldom clearly removed from caudal margin. Legs rather short to long, ♂ ones often stouter and longer, sometimes with peculiar, bi- or trifid ventral trichomes, but sphaerotrichomes missing.

Gonopods peculiar in having rather small, subglobose, medially fused coxae nearly fully exposed in a small gonocoel; coxae at most only slightly setose ventrally, supporting usual cannulae medially and elongated, sometimes strongly curved telopodites laterally; the latter directed dorsolaterad, curving, often very strongly, around coxae 8 along sides of segment 7; seminal groove running along most of telopodite on caudal face to terminate distally either on a special branch or tooth (= solenomere), or flush open on caudal surface, or debauching inside an accessory seminal chamber which normally, but not always, is supplied with a hairy pulvillus.

Type genus.

Opisotretus Attems, 1907.

Remarks.

The above somatic features of Opisotretidae are in no way unique to the family, at least sometimes being also encountered, in various combinations, in the other families of the micropolydesmoid superfamily Trichopolydesmoidea , such as Fuhrmannodesmidae , Trichopolydesmidae , Macrosternodesmidae , Mastigonodesmidae and Nearctodesmidae (e.g. Golovatch 1994, 2011). This can also be said about the basically finely microspiculate limbus obviously characteristic of most of the Polydesmidea . It is only the gonopod structure that is truly characteristic of Opisotretidae , the family formally representing a superfamily of its own, the Opisotretoidea ( Simonsen 1990). Superficially, female and/or juvenile Opisotretidae are not or only barely distinguishable from the often sympatric or even syntopic female or juvenile Fuhr mannodesmidae, the latter family dominating most of the tropical micropolydesmoid faunas. In this connection, we rather believe that Opisotretidae is also a family of Trichopolydesmoidea , probably the closest to Fuhrmannodesmidae (see below).