Onomeris Cook, 1896

Wesener, Thomas, 2010, Revision of the American Pill Millipedes I: Onomeris and Trichomeris (Diplopoda, Glomerida, Glomeridae), Zootaxa 2725, pp. 28-40: 31-32

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http://doi.org/ 10.5281/zenodo.199966

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Onomeris Cook, 1896


Genus Onomeris Cook, 1896 

Onomeris Cook, 1896: 43  . Type species O. underwoodi 

– Chamberlin & Hoffman 1958: 12; Jeekel 1971: 16; Mauriès 1971: 434; Hoffman 1980: 68; Hoffman 1999: 17; Mauriès 2005: 243 (list genus name).

Trichomeris Loomis, 1943: 374  . New synonymy Type species: T. sinuata  – Chamberlin & Hoffman 1958: 13; Jeekel 1971: 18; Hoffman 1980: 68; Hoffman 1999: 18 (list genus name).

The redescription of the genus is presented here in more detail in order to focus the following redescriptions of the species on the unique characters of each species.

Type species: Onomeris underwoodi Cook, 1896 

Other species included: Onomeris australora Hoffman, 1950  ; Onomeris sinuata ( Loomis, 1943)  new comb.

Genus diagnosis: Shares the general shape of telopods, with a prefemoral and a femoral trichostele, a prefemoral process, and especially the presence of a differentiated process on the femur ( Fig. 5View FIGURE 5 B), only with species of the Asia genus Hyleoglomeris  . Tarsus and tibial process of telopod generally of slender appearance ( Fig. 5View FIGURE 5 A). Differs from Hyleoglomeris  and most other genera of Glomeridae  (but not the European Tectosphaera Mauriès, 2005  ) in presence of a strongly modified head, which bears a conspicuous Y-shaped ledge on frontal side, and laterally of crest above organ of Tömösváry large grooves for antennae ( Fig. 1View FIGURE 1 A). Thoracic shield with a large hyposchism field bearing numerous transverse striae whose caudal edge is drawn behind tergal contour, a clear impression present before hypochism ( Fig. 1View FIGURE 1 B). Like in Hyleoglomeris  but unlike Glomeris  male leg 17 greatly reduced in size, with a high outer coxal lobe and a 3 -segmented, vestigial telopodite with an apical spine ( Fig. 2View FIGURE 2 B).

Redescription: Length of non-stretched but unrolled specimens of both sexes ca 4–5 mm, width 2.2–2.8 mm, respectively.

General coloration clearly visible in the type series of O. sinuata  and O. australora  , faded in the type series of O. underwoodi  , but relatively well conserved in more recently collected material of O. underwoodi  and O. sinuata  . Dark brown with laterally lighter grey markings. In the field, specimens are of a shiny appearance resembling micro-gastropods. Tergites 2–11 laterally on metazona with oval greyish-white area, which does not reach margins of tergite. Center of collum light grey; center of head light, margins of head as well as lateral grooves dark brown. Antenna and legs dark brown.

Head with a setose labrum ( Fig. 1View FIGURE 1 A). Head centrally with Y-shaped crest rising between antennae and expanding to posterior margin. Laterally of crest, from posteriorly of antennae and organ of Tőmősváry to ocelli with deep antennal grooves ( Fig. 1View FIGURE 1 A).

Ocellaria  black, ocelli 5 + 1 ( O. underwoodi  ) or 6 + 1; lenses convex ( Fig. 1View FIGURE 1 A).

Antennae with four large apical cones, antennomere 6 ca 2.1 ( O. underwoodi  ) – 2.5 times as long as broad. Antennomere 3 as long as 1 and 2 combined ( Fig. 1View FIGURE 1 A).

Organ of T ő m ő sváry elongate, ca 2.4–2.5 times as long as broad ( Fig. 1View FIGURE 1 F).

Gnathochilarium lateral palps more slender and with fewer sensory cones than inner palps ( Fig. 1View FIGURE 1 D). Central pads and endochilarium on inner side centrally with circa 15 sensory cones in a circular arrangement; more laterally with another area of circa 10 cones ( Fig. 1View FIGURE 1 E).

Mandible: external tooth with a small notch on dorsal side. Inner tooth 4 -combed; four rows of pectinate lamellae; condylus a barely detectable 'bump', weakly developed ( Fig. 2View FIGURE 2 A).

Collum with two transverse striae ( Fig. 1View FIGURE 1 C).

Thoracic shield with a large hyposchism field whose caudal edge is drawn behind tergal contour ( Fig. 1View FIGURE 1 B). Clear impression present in front of schism. Shield with numerous transverse striae, of which three or four cross the dorsum ( Fig. 1View FIGURE 1 B). Striae 1 or 2 striae lie above, 5 or 6 level to, and further 4 or 5 posterior to the schism ( Fig. 1View FIGURE 1 B). Thoracic shield like other tergites sparsely covered with numerous minute pits ( Fig. 1View FIGURE 1 B), a short setae rising at each pit.

Following tergites 3–11 covered with numerous short setae ( Fig. 4View FIGURE 4 A), usually inserting in a pit ( Fig. 4View FIGURE 4 B). Dorsal ozopore without any conspicuous ridges. Anterior margin of tergites with wavy ridge projecting posteriorly in a tooth-like pattern ( Fig. 4View FIGURE 4 A). Tergites laterally without discernable striae, lateral edges not projecting posteriorly.

Male anal shield at least faintly ( O. sinuata  ), more often strongly concave medially at caudal edge ( Fig. 5View FIGURE 5 E).

Male leg 17 ( Fig. 2View FIGURE 2 B) particularly strongly reduced, with a low, broad, rounded coxal lobe and a 3 -segmented vestigial telopodite.

Male leg 18 ( Fig. 3View FIGURE 3 A) less strongly reduced, with a syncoxial notch and a 4 -segmented telopodite. Second joint of telopodite flattened, last telopodite with strongly developed spine ( Fig. 3View FIGURE 3 A)

Telopod ( Figs 3View FIGURE 3 B, 5 A –C) strongly robust, with a high, roundly subtrapeziform ( Fig. 3View FIGURE 3 B) to bilobed ( Fig. 6View FIGURE 6 C) syncoxital lobe flanked by setose, apically simple horns. Prefemur with strongly developed trichostele. Femur with trichostele of circa half the length of the prefemur one, posteriorly with very large, triangular process. Femur with strongly sclerotized, distal finger on posterior side, as well as a field of sclerotized teeth located centrally on the posterior face of finger ( Fig. 5View FIGURE 5 B). Tibia and tarsus, as well as tarsus and femoral process forming a chela ( Fig. 5View FIGURE 5 A). Tibia with long, strongly sclerotized, but slender distal finger caudolaterally; finger with a small field of sclerotized teeth at its base ( Fig. 3View FIGURE 3 B). Tarsus slender, basally curved 45–65 degrees towards syncoxite, otherwise straight ( Fig. 3View FIGURE 3 B), inner margin towards femoral process with sclerotized teeth ( Fig. 3View FIGURE 3 B). Apex of tarsus well-rounded, posteriorly with curved spine ( Fig. 3View FIGURE 3 B).

Synonymization of Trichomeris Loomis, 1943  under Onomeris Cook, 1896  . The synonymization of Trichomeris  und Onomeris  was suggested previously ( Hoffman 1999, p. 18: "This monotypic genus is probably not separable from Onomeris  "). Re-study of the type specimen of T. sinuata  , the only described Trichomeris  species, shows that this species indeed belongs into Onomeris  . The telopod differences between T. sinuata  and Onomeris  species, which even prompted the different systematic placement of both by Mauriès (1972, 2005), were based on erroneous drawings by the first describer.

Position of the genus Onomeris  within the Glomerida  . Currently, authors agree that Onomeris  should be placed in the pill millipede family Glomeridae  (Hoffman 1980, Mauriès 2005), based on the presence of setae and an outgrowth on the mesal side of the telopod ( Fig. 5View FIGURE 5 A). On the tribe level, the position of Onomeris  needs to be fixed through a phylogenetic analysis, which is beyond the scope of this study. In the most recent system ( Mauriès 2005), Onomeris  is placed in the tribe Glomerini together with the mainly West European genera Glomeris  , Sicilomeris  and Loboglomeris  , while Trichomeris  is not mentioned. However, according to the character descriptions ( Mauriès 2005), the presence of a differentiated process on the femur, which is clearly present in Onomeris  ( Fig. 5View FIGURE 5 A), would place this genus in the large tribe Dooderiini, and there particularly close to the Asian genus Hyleoglomeris  (see Golovatch et al. 2006, 2010).












Onomeris Cook, 1896

Wesener, Thomas 2010


Hoffman 1999: 18
Chamberlin 1958: 13
Loomis 1943: 374


Cook 1896: 43