Proceratium shohei Staab, Xu & Hita Garcia

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 shohei Staab, Xu & Hita Garcia sp. n. Figs 3A, 3C, 22, 23, 25

Type material.

Holotype. Pinned worker from CHINA, Yunnan Province, Xishuangbanna, Kilometer 55 station, 21.964°N / 101.202°E, 820 m asl, rain forest, Winkler leaf litter extraction, 13-VI-2013, leg. Benoit Guénard, Benjamin Blanchard & Cong Liu, label ‘05121’ (CASENT0717686), deposited in SWFU.

Cybertype. Volumetric raw data (in DICOM format), 3D rotation video (in mp4 format, see Suppl. material 10: Video 8), still images of surface volume rendering, and 3D surface (in PLY format) of the physical holotype (CASENT0717686) 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 type. In addition to the cybertype data at Dryad, we also provide a freely accessible 3D surface model of the holotype at Sketchfab (https://sketchfab.com/models/0dd8217041274f268fae8897958d9b6a).

Diagnosis.

Proceratium shohei differs from the other oriental members of the P. stictum clade by the following character combination: head broadest at the level of eyes, sides and vertex of head weakly convex, almost straight; scapes relatively long (SI 72); frontal carinae relatively broad and slightly convex; posterodorsal corners of propodeum with broad teeth that project over less than half of the propodeal lobes in profile; petiole in dorsal view longer than broad; petiolar node relatively compressed dorsoventrally, subpetiolar process inconspicuous, a lamellae only, without a projection; LS3 with a straight ventral outline; abdominal segment IV strongly recurved and broadly rounded, LS4 reduced (IGR not measurable); head, mesosoma, petiole, and LT3 foveolate; LT4 smooth and shiny, dorsally without sculpture, laterally superficially punctured.

Worker measurements.

Holotype.TL 4.15; EL 0.09; SL 0.71; HL 0.99; HLM 1.13; HW 0.89; WL 1.25; MFeL 0.89; MTiL 0.71; MBaL 0.56; PeL 0.47; PeW 0.44; LT3 0.64; LS4 n.a.; LT4 0.66; OI 10; CI 90; SI 72; MFeI 100; MTiI 80; MBaI 63; DPeI 94; IGR n.a.; ASI 103.

Worker description.

In full-face view, head slightly longer than broad (CI 90), sides and vertex weakly convex, almost straight. Clypeus relatively broad, surrounding antennal insertions and protruding anteriorly, anterior clypeal margin with a distinct notch. Frontal carinae relatively short, broadly separated from each other, constantly diverging posteriorly and not covering antennal insertions, lateral expansions of frontal carinae slightly concave in full-face view; frontal area convex; frontal furrow absent. Genal carinae strongly developed; ventral face of head (gular area) concave. Eyes relatively large (OI 10), consisting of one convex ommatidium, located slightly anterior to the midline of head. Antennae 12-segmented, scapes comparatively long (SI 72), not reaching posterior head margin and thickening apically. Mandibles elongate and triangular, masticatory margin with three teeth in total, apical tooth large and acute, the other teeth smaller and decreasing in size from second to third tooth that is followed by a series of minute blunt denticles.

Mesosoma in profile convex and longer than maximum head length including mandibles. Lower mesopleurae (katepisterna) with demarcated sutures, upper mesopleurae (anepisterna), and promesonotum with inconspicuous and very shallow sutures; lower mesopleurae inflated posteriorly; posterodorsal corners of propodeum with broad teeth that project over less than half of the propodeal lobes in profile, propodeal lobes strongly developed as broadly triangular teeth protruding dorsolaterally; propodeal declivity almost vertical, slightly inclined anteriorly; in posterodorsal view, sides of propodeum separated from declivity by lamellate margins; propodeal spiracle relatively small, located above mid height; in profile, opening ellipsoid and facing posteriorly. Legs comparatively long; all tibiae with a pectinate spur; calcar of strigil with a basal spine; pretarsal claws simple; arolia present.

Petiole in dorsal view longer than broad, sides consistently diverging posteriorly, anterior border with a thick margin that is distinctly angulate on each side; in profile, petiolar node relatively compressed dorsoventrally, its anterior face slightly sloping; dorsum of node relatively flat, weakly convex; ventral face inconspicuous with a thin lamella and no projection.

In dorsal view, abdominal segment III anteriorly much broader than petiole, its sides weakly convex; abdominal sternite III extended ventrally, its outline straight, anteriomedially with a conspicuous depression marked by a broad rim. Constriction between abdominal segments III and IV deep. Abdominal segment IV very large, very strongly recurved (abdominal sternum IV reduced and IGR not measurable) and posteriorly rounded, with a thin lamella on its anterior border; abdominal tergum IV slightly longer than abdominal tergum III (ASI 103), remaining abdominal tergites and sternites inconspicuous and projecting anteriorly. Sting large and extended.

Whole body covered with dense relatively short decumbent to erect hairs; additionally significantly longer suberect to erect hairs abundant on the whole body, including legs and scapes; such hairs also present on funicular joints, but shorter and relatively thicker; dense appressed to decumbent pubescence on the funiculus only; mandibles striate; head, mesosoma, petiole, and abdominal segment III foveolate with superimposed punctures and granules, the foveae relatively deep, large, and irregular; abdominal segment IV smooth and shiny, dorsally without sculpture, laterally superficially punctured; scapes and legs densely punctured. Body color uniformly dark ferruginous-brown, antennae, legs, and abdominal segments V–VII orange brown.

Etymology.

This species is named in honor of Dr. Shohei Suzuki (1979-2016), a Japanese marine biologist whose life was tragically lost in a diving accident while conducting coral reef research in Okinawa.

Distribution and ecology.

No direct observations of biology and natural history are available. The type specimen was collected from rain forest leaf litter. Like many other ant species occurring in the tropical rain forest of Xishuangbanna, the species probably also occurs in adjacent countries such as Laos or Thailand.

Taxonomic notes.

In Liu et al. (2015b) this species was erroneously listed as P. deelemani , a species known from Borneo, peninsular Malaysia, and Thailand (see Baroni Urbani and de Andrade 2003). However, a careful reexamination of the specimen from Yunnan and comparisons with images of the holotype of P. deelemani (CASENT0915370) and further P. deelemani specimens from Borneo (CASENT0790842, CASENT0790847, CASENT0790848; see Suppl. material 2: Figure S1 for micro CT images of CASENT0790842 and see Suppl. material 11: Video 9 for a 3D rotation video of the same specimen) revealed considerable morphological differences that convinced us to separate both species and to describe P. shohei as new. Among the other species of the P. stictum clade occurring in the oriental zoogeographic region ( P. deelemani , P. foveolatum , P. stictum ), P. shohei is unsurprisingly most similar to P. deelemani , but both species can be safely and easily separated. Proceratium shohei has an indistinct subpetiolar process without a median anterior projection (subpetiolar process with a distinct tooth in P. deelemani ; opposed to the P. itoi clade, the subpetiolar process is an informative character in the P. stictum clade). Also, P. shohei has relatively longer scapes (SI 72) (SI 58-68 in P. deelemani ), the posterodorsal corner of the propodeum with relatively shorter teeth that project over less than half of the length of the propodeal lobes in profile (at least projecting over half of propodeal lobes in P. deelemani ), a very reduced LS4 so that IGR cannot be measured (LS4 also reduced but IGR 0.23-0.29 in P. deelemani ), a straight ventral outline of LS3 (with a depression in P. deelemani ), and slightly convex frontal carinae (slightly concave in P. deelemani ). Superficially, P. shohei also resembles P. stictum and P. foveolatum . From P. stictum it can be distinguished by the subpetiolar process without a median anterior projection (subpetiolar process with a distinct tooth in P. stictum ), the longer teeth on the posterodorsal corners of the propodeum that project straightly backwards (short and blunt, projecting slightly dorsally in P. stictum ), and the foveolate sculpture of the head, mesosoma, petiole, and LT3 (coarsely granulate with superimposed fovea in P. stictum ). The sculpture of the integument likewise easily distinguishes P. shohei from P. foveolatum , which has the entire integument including LT4 covered with large, deep, regular, and clearly demarcated fovea (fovea smaller and shallower, at most superficial punctures but no fovea on LT4 in P. shohei ). Also, in P. foveolatum LT4 is extended posteriorly and forms a broad, strong angle while LT4 is not as extended and broadly rounded in P. shohei .

Variation.

Since this species is known only from the holotype there is no available information about intraspecific variation.