Paratrechina umbra

Identification
Williams and LaPolla (2016) - This species was likely thought to be a Prenolepis because its elongate mesosoma appears to be constricted. Paratrechina umbra however does not have the depression in the dorsal surface of the mesonotum that is seen in Prenolepis species. This species also has deep and complete mesonotal and metanotal sutures.

Paratrechina umbra has features consistent with Paratrechina morphology (LaPolla & Fisher 2014), including elongate scapes (SI > 170) with dense pubescence and a head that is distinctly longer than wide (CI < 81). Paratrechina umbra has slightly anteriorly-placed eyes (EPI < 100) and 6 teeth on the masticatory margin, which are features consistent across Nylanderia species (LaPolla et al. 2010a). However, we have also found that like all Paratrechina, P. umbra has longitudinal striations across the ectal surface of the mandibles a feature that has never been observed in Nylanderia species. Based on these findings in addition to molecular evidence (S.G. Brady, unpublished data), we place P. umbra in Paratrechina. This means that P. umbra is the only Paratrechina species found only in Asia and Paratrechina longicornis is no longer the only Paratrechina species to be found outside of Africa (LaPolla et al. 2013).

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Nomenclature

 *  umbra. Prenolepis umbra Zhou & Zheng, 1998a: 43, figs. 3, 4 (w.) CHINA.
 * Status as species: Zhou, 2001b: 171.
 * Combination in Paratrechina: Williams & LaPolla, 2016: 250.

Worker
Williams and LaPolla (2016) - (n=13): CMC: 4–8; EL: 0.19–0.24; EW: 0.15–0.17; HL: 0.81–0.92; HLA: 0.35–0.38; HLP: 0.37–0.40; HW: 0.62–0.70; IOD: 0.47–0.48; LF1: 0.21–0.22; LF2: 0.11–0.13; LHT: 1.12–1.26; MMC: 0–2; MTW: 0.41–0.47; MW: 0.28–0.33; PDH: 0.36–0.41; PMC: 0–1; PrCL: 0.58–0.64; PrCW: 0.34–0.38; PrFL: 0.96–1.06; PrFW: 0.23–0.24; PTH: 0.37–0.40; PTL: 0.30–0.33; PTW: 0.19–0.22; PW: 0.50–0.56; SL: 1.16–1.27; TL: 3.08–3.77; WF1: 0.07–0.08; WF2: 0.07–0.08; WL: 1.17–1.43; BLI: 182–210; CI: 76–81; EPI: 93–97; FLI: 167–191; HTI: 167–185; PetHI: 101–102; PetWI: 64–69; PrCI: 59–62; PrFI: 23– 24; REL: 23–28; REL2: 30–35; REL3: 40–49; SI: 173–187.

Dark brown to black with yellow to light brown legs and antennae; entire cuticle lightly to finely reticulate; dark, erect macrosetae with thick setal bases on head, gaster, and legs; erect macrosetae on head is sparse (CMC < 8); sparse erect setae and dense pubescence on scapes; no erect macrosetae on pronotum, mesonotum, metanotum, or propodeum; fine, dense pubescence covering most of the cuticle; head longer than broad and rectangular in shape with indistinct posterolateral corners and slight medial concavity in the posterior margin; compound eyes are positioned at or anterior to the midline of the head (EPI < 100); eyes are moderately sized and convex, but do not surpass the lateral margins of the head in full-face view; mandibles with 6 teeth on the masticatory margin; cuticle of ectal surface of mandibles has light longitudinal striations; mesosoma is gracile; in profile view the dorsal surface of the mesonotum is flat and elongate; in profile view, propodeum is highly domed with a rounded dorsal face; mesonotal and metanotal sutures are deep and complete; dorsal apex of petiole scale is sharply angled and forward-inclined.

Type Material
Williams and LaPolla (2016) - Holotype worker, China: Guangxi Province, Huaping Nature Reserve, 25°10.10’N 109°48.54’E, 534m, 5.vii.1995 [examined].