Nearctomeris inexpectata, Wesener, Thomas, 2012

Wesener, Thomas, 2012, Nearctomeris, a new genus of Pill Millipedes from North America, with a comparison of genetic distances of American Pill Millipede Genera (Glomerida, Glomeridae), Zootaxa 3258, pp. 58-68 : 63-65

Nearctomeris inexpectata , new species

Etymology. inexpectata , adjective, meaning 'unexpected', referring to the surprise of the describer when he found a second, undescribed genus and species among the sample of Onomeris sinuata specimens.

Material examined. Holotype: 1 M, ZFMK MYR 008, USA, Alabama, Huntsville, Monte Sano State Park, under logs and in leaf litter next to limestone outcrops, NE shadow, 34 ° 44 ' 10.30 " N, 086° 30 '00.10" W, leg. T. Wesener & H. Walsh, 30.iii.-01.iv. 2010. Gen Bank # JQ 074186

Paratypes: 1 F, ZFMK MYR 005, same data as holotype; 1 F, 1 imm. ZFMK MYR 010, same data as holotype; 4 imm., ZFMK MYR 011, same data as holotype; 1 F TWAL 16 FMNH-INS 0 0 0 0 0 73 489.

Other material. 2 M, 6 F, VMNH, USA, North Carolina, Macon County, Wayah Bald, Natahales, coll. RL Hoffman, 03.vi. 1953 (together with 1 imm. M, 1 F Onomeris ); 4 F VMNH (labeled as 'Types' by R.L. Hoffman, not selected as types of N. inexpectata because they are female), Tennessee, Polk County, Tellico Gorge, coll. L. Hubricht, 11.vi. 1953.

Diagnosis. Small-bodied (< 6 mm), darkly colored ( Fig. 2 A) pill-millipede. Co-occurs with Onomeris species. See key for a distinction between Nearctomeris inexpectata and different Onomeris species.

Description. Measurements: largest female of type series: 5.3 mm long, thoracic shield 2.6 mm wide, tergite 5 2.85 mm wide, thoracic shield 1.8 mm high. Holotype male fragmented due to dissection and tissue extraction, smaller than female.

General coloration ( Fig. 2 A) blackish-brown, each tergite laterally with a lighter, central, almost white area (muscle insertion?). Head, antenna and legs dark brown. In the field, specimens are of a shiny appearance, resembling micro-gastropods.

Head with a setose labrum covered by eight marginal setae ( Fig. 2 C). Lateral margins well-rounded. Head like tergites sparsely covered with minute setae ( Fig. 2 D).

Ocellaria black, ocelli 6 + 1 (in smaller specimens also 5 + 1 or 4 + 2); lenses convex ( Fig. 3 C).

Antennae with four large apical cones, antennomere 6 approximately 2 times as long as broad. Antennomere 3 as long as 1 and 2 combined ( Fig. 2 C).

Organ of Tömösváry elongate, about 2.4–2.5 times as long as broad ( Fig. 2 C).

Gnathochilarium ventrally without any peculiarities ( Fig. 2 D), not dissected, endochilarium unknown.

Mandible ( Figs 3 A, B) with large basal joints ( Fig. 2 D). Inner tooth 5 -combed; seven rows of pectinate lamellae; large intermediate area consisting of sclerotized, finely combed teeth between pectinate lamellae and molar plate ( Fig. 3 B). Condylus absent, or a barely detectable 'bump' ( Fig. 3 A).

Collum with two transverse striae ( Fig. 2 F), covered sparsely with minute, short hair like the rest of the tergites.

Thoracic shield with weakly developed schism, its caudal edge not protruding above tergal contour ( Fig. 2 E). Weak, almost slit-like impression present in front of schism. Shield with few transverse striae, of which only one crosses the dorsum ( Fig. 2 E). Two more incomplete striae present dorsally ( Fig. 2 E: str 2 & str 3) The complete stria and one short stria lie below, several inside, and two very short ones above the impression ( Fig. 2 E). Thoracic shield, like other tergites, sparsely covered with numerous minute pits ( Fig. 2 E), a short seta arising at each pit.

Following tergites 3–11 covered with numerous short setae, usually inserting in pits. Anterior margin of tergites with a well rounded marginal ridge ( Fig. 2 E). Tergites laterally with a single discernable stria, lateral edges not projecting posteriorly ( Fig. 2 A).

Mid-body legs ( Fig. 3 G) at mesal margin with numerous setae. Femur 2.0 times longer than wide, tarsus slender, tapering towards apex, 3.9 –4.0 times longer than wide. Tarsus with 9–12 ventral spines, one apical spine, and additional 6 or 7 dorsal spines. Claw long and slender.

Male anal shield well-rounded, without any kind of notch or a concave posterior margin ( Fig. 2 B).

Male first leg pair ( Fig. 4 A) similar to mid-body legs, but coxae mesally elongated into a process carrying a single long spine. Tarsus with only seven ventral spines.

Male second leg pair ( Fig. 3 D) similar to mid-body legs, but coxae mesally with single spine of mediumlength. Femur slender, 3.0 times longer than wide. Gonopore covering mesal 1 / 3 of coxa.

Male gonopore ( Figs 4 E, F) consisting of a single opening covered by an apparently membranous operculum. Bursa apico-mesally with a field of long setae.

Male leg 17 ( Fig. 4 B) particularly strongly reduced, with a low, broad, rounded coxal lobe and a 3 -segmented vestigial telopodite. First and second podomere with a mesal, third podomere with an apical spine.

Male leg 18 ( Fig. 4 C) less strongly reduced, with a syncoxial notch, coxite mesally elongated into a short process carrying a large spine. Apically of syncoxite with a 4 -segmented telopodite, podomere 4 with strongly developed spine ( Fig. 3 A).

Telopod ( Figs 4 D–G) strongly robust, with a high, rounded, subtrapeziform ( Figs 4 F, G) syncoxital lobe flanked by setose, apically simple horns. Inner horns mesally with single spine whose base is curved 90 °. Prefemur with strongly developed trichostele. Femur with trichostele approximately a third of the length of the prefemoral one, posteriorly with very large, well-rounded process (= distal finger). Femur with a field of sclerotized teeth located centrally on the posterior face of finger ( Fig. 4 D). Tibia, tarsus, and distal finger forming a chela ( Fig. 4 D). Tibia with a small field of sclerotized teeth at its base ( Fig. 4 D). Tarsus long, massive, basally curved 45–65 degrees towards syncoxite ( Fig. 4 E). Apex of tarsus well-rounded, posteriorly with long spine. Telopod posteriorly only sparsely covered with few, isolated setae, on anterior side glabrous.

Intraspecific variation. Specimens from North Carolina ( VMNH) show the following measurements: small male: 4.9 mm long, at thoracic shield 2.5 wide, with 5 + 1 ocelli, largest female 5.6 mm long, at thoracic shield 2.7 wide, with 6 + 1 ocelli.