Proceratium longigaster Karavaiev, 1935

Staab, Michael, Garcia, Francisco Hita, Liu, Cong, Xu, Zheng-Hui & Economo, Evan P., 2018, Systematics of the ant genus Proceratium Roger (Hymenoptera, Formicidae, Proceratiinae) in China - with descriptions of three new species based on micro-CT enhanced next-generation-morphology, ZooKeys 770, pp. 137-192 : 137

Proceratium longigaster Karavaiev, 1935 Figs 2A, 20, 21, 25

Proceratium longigaster Karavaiev, 1935: 59 (w.), Vietnam (see also Xu 2000: 436, Baroni Urbani and de Andrade 2003: 438)

Type material.

Holotype. VIETNAM, Central Annam, close to Tourane, Bana, 1400 m asl, 30-IX.1931, leg. K. Davydov (CASENT0916806, in SIZK) [images examined].

Non-type material examined.

CHINA, Zhejiang Province, Gutianshan National Nature Reserve, ca. 30 km NW of Kaihua, 29°15'3"N, 118°8'34"E, 890 m asl, secondary subtropical mixed forest, Winkler extraction of a rotten log, 27-IV-2015, leg. Merle Noack, all with label ‘MS1857’ (CASENT0790844 in CASC; CASENT0790673 and CASENT0790843 in SWFU; CASENT0790845 in BMNH; CASENT0790846 in ZMBH).

Virtual dataset.

Volumetric raw data (in DICOM format), 3D rotation video (in.mp4 format, see Suppl. material 9: Video 7), still images of surface volume rendering, and 3D surface (in PLY format) of a non-type specimen (CASENT0790673) in addition to montage photos illustrating head in full-face view, profile and dorsal views of the body. The data is deposited at Dryad ( Staab et al. 2018, http://dx.doi.org/10.5061/dryad.h6j0g4p) and can be freely accessed as virtual representation of the species. In addition to the data at Dryad, we also provide a freely accessible 3D surface model at Sketchfab (https://skfb.ly/6txOA).

Diagnosis.

Proceratium longigaster differs from the other east Asian members of the P. silaceum clade by the following character combination: medium-sized species (WL 0.75-0.89); sides of head slightly convex, broadest directly above the level of eyes; anterior clypeal margin not protruding and slightly notched; frontal carinae well developed and widely separated, with large lamellae that extend laterally above the antennal insertions and reach posteriorly about half the distance to the level of eyes; frontal furrow strongly developed; petiole squamiform; in profile, narrowing dorsally, the base clearly broader than the apex; in dorsal view, relatively wide (DPeI ≥155); subpetiolar process developed, subtriangular, directing backwards and relatively acute; sculpture deeply impressed, on abdominal segment III irregularly granular to reticulate (more so on dorsum); very hairy species; in addition to dense pubescence, many appressed to erect hairs present on entire body; abundant, long appressed, shaggy hairs project from LT3 distinctly over the constriction between LT3 and LT4.

Worker measurements.

(n=5).TL 2.66-3.10; EL 0.03-0.04; SL 0.42-0.46; HL 0.65-0.70; HLM 0.71-0.92; HW 0.60-0.66; WL 0.75-0.89; MFeL 0.43-0.54; MTiL 0.35-0.42; MBaL 0.26-0.29; PeL 0.20-0.22; PeW 0.31-0.34; LT3 0.43-0.49; LS4 0.28-0.30; LT4 0.56-0.63; OI 5; CI 92-98; SI 65-66; MFeI 71-83; MTiI 58-65; MBaI 42-45; DPeI 155-157; IGR 0.47-0.50; ASI 123-138.

Distribution and ecology.

The type locality is at ca. 1400 m asl in the Bà Nà hills close to Đà Nẵng city (referred to as Tourane in the original description), central Vietnam. The species is also known form Nangongshan Mountain, Mengla County, Yunnan Province ( Xu 2000) (1525 m asl) and from Hunan Province ( Guénard and Dunn 2012). In the places where it is known, specimens were collected from the ground in evergreen broadleaved forest. The new record from the Gutianshan National Nature Reserve, Zhejiang Province, is no exception in being from the same forest type albeit at lower elevation (890 m asl) and marks the easternmost distribution of the species. Thus, P. longigaster seems to be widespread in suitable forest habitats in south and east China and adjacent countries. No direct observations of biology and natural history are available.

Taxonomic notes.

This is a poorly known species. Since the single type specimen was not available for examination, Baroni Urbani and de Andrade (2003) were unable to formally treat it in their monograph. Karavaiev’s (1935) type specimen is lodged in the Schmalhausen Institute of Zoology (Kiev, Ukraine) and cannot be obtained as a loan. Fortunately, though, it has recently been imaged and the montage photos are available on AntWeb (CASENT0916806). Our new specimens agree with the type and the accounts of Xu (2000). Thus, with a note of caution, we feel confident enough to treat the specimens from Zhejiang Province as P. longigaster .

The only other P. silaceum clade species known from China and east Asia is P. japonicum , from which P. longigaster can be separated by the shape of the petiolar node, the frontal carinae, and the pilosity, among other characters (see the accounts for P. japonicum above).