Proceratium longigaster

Proceratium longigaster seems to be widespread in suitable forest habitats in south and east China and adjacent countries.

Identification
Staab et al. (2018) - Proceratium longigaster differs from the other east Asian members of the Proceratium 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.

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 Proceratium longigaster.

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

Volumetric raw data (in DICOM format), a 3D rotation video (in .mp4 format, see Suppl. material9: Video 7), still images of surface volume rendering, a 3D surface (in PLY format), and montage photos illustrating the head, profile and dorsal views of the body of a non-type specimen (CASENT0790673) were all generated as part of this study (Staab et al 2018). Data and images are freely available for download from a Dryad repository (there is a download link at the top right of the webpage) and a 3D surface model can be viewed online at Sketchfab.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam. Palaearctic Region: China.

Biology
Staab et al. (2018) - 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, Proceratium 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.

Nomenclature

 *  longigaster. Proceratium longigaster Karavaiev, 1935a: 59, fig. 2 (w.) VIETNAM. See also: Xu, 2000c: 436; Baroni Urbani & De Andrade, 2003b: 438.

Worker
Staab et al. (2018) - (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.

Type Material
Staab et al. (2018) - Holotype. VIETNAM, Central Annam, close to Tourane, Bana, 1400 m asl, 30-IX.1931, leg. K. Davydov (CASENT0916806, in ) [images examined].

References based on Global Ant Biodiversity Informatics

 * Fontanilla A. M., A. Nakamura, Z. Xu, M. Cao, R. L. Kitching, Y. Tang, and C. J. Burwell. 2019. Taxonomic and functional ant diversity along tropical, subtropical, and subalpine elevational transects in southwest China. Insects 10, 128; doi:10.3390/insects10050128
 * Staab M., F. Hita Garcia, C. Liu, Z. H. Xu, and E. P. Economo. 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: 137-192.
 * Xu Z. H. 2000. A systematic study of the ant genus Proceratium Roger from China (Hymenoptera: Formicidae). Acta Zootaxonomica Sinica 25(4): 434-437.
 * Xu Z. 2000. A systematic study of the ant genus Proceratium Roger from China (Hymenoptera: Formicidae). Acta Zootaxonomica Sinica 25(4): 434-437.