Onomeris Cook 1896
Creators: name: Wesener, Thomas
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Glomerida
Glomeridae
Onomeris

description: 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. 5 B), only with species of the Asia genus Hyleoglomeris. Tarsus and tibial process of telopod generally of slender appearance (Fig. 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. 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. 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. 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. 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. 1 A).
Ocellaria black, ocelli 5+1 (O. underwoodi) or 6+1; lenses convex (Fig. 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. 1 A).
Organ of T ő m ő sváry elongate, ca 2.4–2.5 times as long as broad (Fig. 1 F).
Gnathochilarium lateral palps more slender and with fewer sensory cones than inner palps (Fig. 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. 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. 2 A).
Collum with two transverse striae (Fig. 1 C).
Thoracic shield with a large hyposchism field whose caudal edge is drawn behind tergal contour (Fig. 1 B). Clear impression present in front of schism. Shield with numerous transverse striae, of which three or four cross the dorsum (Fig. 1 B). Striae 1 or 2 striae lie above, 5 or 6 level to, and further 4 or 5 posterior to the schism (Fig. 1 B). Thoracic shield like other tergites sparsely covered with numerous minute pits (Fig. 1 B), a short setae rising at each pit.
Following tergites 3–11 covered with numerous short setae (Fig. 4 A), usually inserting in a pit (Fig. 4 B). Dorsal ozopore without any conspicuous ridges. Anterior margin of tergites with wavy ridge projecting posteriorly in a tooth-like pattern (Fig. 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. 5 E).
Male leg 17 (Fig. 2 B) particularly strongly reduced, with a low, broad, rounded coxal lobe and a 3-segmented vestigial telopodite.
Male leg 18 (Fig. 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. 3 A)
Telopod (Figs 3 B, 5A–C) strongly robust, with a high, roundly subtrapeziform (Fig. 3 B) to bilobed (Fig. 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. 5 B). Tibia and tarsus, as well as tarsus and femoral process forming a chela (Fig. 5 A). Tibia with long, strongly sclerotized, but slender distal finger caudolaterally; finger with a small field of sclerotized teeth at its base (Fig. 3 B). Tarsus slender, basally curved 45–65 degrees towards syncoxite, otherwise straight (Fig. 3 B), inner margin towards femoral process with sclerotized teeth (Fig. 3 B). Apex of tarsus well-rounded, posteriorly with curved spine (Fig. 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. 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. 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).
description: Published as part of Wesener, Thomas, 2010, Revision of the American Pill Millipedes I: Onomeris and Trichomeris (Diplopoda, Glomerida, Glomeridae), pp. 28-40 in Zootaxa 2725 on pages 31-32, DOI: 10.5281/zenodo.199966