Proceratium kepingmai 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 kepingmai Staab, Xu & Hita Garcia sp. n. Figs 5B, 7A, 7C, 12, 13, 24

Type material.

Holotype. Pinned worker from CHINA, Jiangxi Province, near the village Xingangshan, ca. 15 km SE of Wuyuan, 29°7'28"N / 117°54'40"E, 270 m asl, secondary subtropical mixed forest, Winkler leaf litter extraction, 26-III-2015, leg. Michael Staab, label “MS1836” (CASENT0790031), deposited in SWFU.

Paratype. Pinned worker from CHINA, Zhejiang Province, Gutianshan National Nature Reserve, ca. 30 km NW of Kaihua, 29°14'50"N / 118°8'10"E, 665 m asl, secondary subtropical mixed forest, Winkler leaf litter extraction, 27-IV-2015, leg. Merle Noack, label “MS1859” (CASENT0790032), deposited in ZMBH.

Cybertype. Volumetric raw data (in DICOM format), 3D rotation video (in.mp4 format, see Suppl. material 5: Video 3), still images of surface volume rendering, and 3D surface (in PLY format) of the physical holotype (CASENT0790031) 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://skfb.ly/6txMy).

Diagnosis.

Proceratium kepingmai differs from the other members of the P. itoi clade by the following character combination: large species (TL 4.39-4.54); sides of head weakly convex, broadest at level of eyes and gently narrowing anteriorly and stronger posteriorly; vertex almost straight; very reduced eyes (OI 2-3) consisting of a single minute ommatidium; frontal carinae well developed, with large lamellae that extend laterally above the antennal insertions; frontal furrow darker than the surrounding anterior cephalic dorsum; posterodorsal corners of the propodeum broadly angular; propodeal declivity densely punctured, mostly opaque; posterior face of petiolar node in profile steeper than anterior face and about half as long as anterior face; apex of petiolar node distinctly broader than long in dorsal view; in addition to dense pubescence, erect hairs present on scapes and dorsal surface of body, longest of those hairs at most as long as the maximum dorsoventral diameter of metafemur.

Worker measurements.

Holotype.TL 4.39; EL 0.02; SL 0.57; HL 0.92; HLM 1.08; HW 0.86; WL 1.14; MFeL 0.71; MTiL 0.60; MBaL 0.44; PeL 0.45; PeW 0.36; LT3 0.64; LS4 0.32; LT4 1.08; OI 2; CI 92; SI 60; MFeI 83; MTiI 70; MBaI 51; DPeI 80; IGR 0.30; ASI 169.

Paratype.TL 4.54; EL 0.03; SL 0.59; HL 0.98; HLM 1.14; HW 0.90; WL 1.24; MFeL 0.79; MTiL 0.65; MBaL 0.48; PeL 0.46; PeW 0.37; LT3 0.65; LS4 0.34; LT4 1.05; OI 3; CI 93; SI 62; MFeI 88; MTiI 72; MBaI 53; DPeI 80; IGR 0.33; ASI 161.

Worker description.

In full-face view, head slightly longer than broad (CI 92-93), sides weakly convex, broadest at the eye level and gently narrowing anteriorly and (stronger) posteriorly, vertex weakly convex, almost straight. Clypeus reduced and narrow, with a broadly triangular median anterior projection. Frontal carinae relatively short, moderately separated, slightly covering antennal insertions, constantly diverging posteriorly, lateral expansions of anterior part of frontal carinae developed as broad lamellae, raised, conspicuously and broadly extending laterally above antennal insertions; frontal area convex; frontal furrow well developed as a raised carina, starting at the clypeal projection and extending over the anterior 2/5 of the cephalic dorsum, with a short gap at the level where the lamellae of frontal carinae are broadest. Eyes reduced, minute (OI 2-3), consisting of a single ommatidium and located on midline of head. Antennae 12-segmented, scapes short (SI 60-62), not reaching posterior head margin and thickening apically. Mandibles elongate and triangular, masticatory margin with four teeth in total, apical tooth long and acute, the other teeth smaller and decreasing in size from second to fourth tooth, gap between second and third tooth larger than between other teeth.

Mesosoma in profile slightly convex and slightly longer than maximum head length including mandibles (WL 1.14-1.24 vs. HLM 1.08-1.14). Lower mesopleurae (katepisterna) with well-demarcated sutures, upper mesopleurae (anepisterna) with inconspicuous sutures, no other sutures developed on lateral and dorsal mesosoma; lower mesopleurae weakly inflated posteriorly; posterodorsal corner of propodeum broadly angular, propodeal lobes weakly developed as bluntly rounded lamellae; propodeal declivity almost vertical, slightly inclined anteriorly; in posterodorsal view sides of propodeum separated from declivity by distinct lamellate margins; in profile propodeal spiracle rounded, at mid height, opening of spiracle slightly facing posteriorly. Legs moderately long; all tibiae with a pectinate spur; calcar of strigil without a basal spine; pretarsal claws simple; arolia present.

Petiolar node in profile high, nodiform, with a straight and sloping anterior face, dorsum of node broadly rounded, posterior face half as long and steeper than anterior face; petiole in dorsal view longer than broad but apex of node clearly broader than long; ventral process moderately developed on anterior petiole, with a relatively indistinct rectangular projection.

In dorsal view abdominal segment III anteriorly much broader than petiole; its sides convex; abdominal sternite III anteriomedially with a conspicuous depression marked by a thin rim. Constriction between abdominal segments III and IV deep. Abdominal segment IV very large, recurved (IGR 0.30-0.33) and posteriorly strongly rounded, with a lamella on its anterior border around the constriction to abdominal segment III, this lamella thicker ventrally than dorsally; abdominal tergum IV 1.6 –1.7× longer than abdominal tergum III (ASI 161-169); remaining abdominal tergites and sternites inconspicuous and projecting anteriorly. Sting large and extended.

Whole body covered with dense mat of short, decumbent to suberect pubescent hairs; additionally, the dorsal surfaces of body interspersed with significantly longer suberect and erect hairs, such hairs also present on abdominal sterna III + IV, scapes (anterior faces of scapes with many hairs, posterior faces with single hairs), and legs (ventral faces of femora and tibiae with many hairs, dorsal faces with single hairs); the longest hairs on dorsal surface of body at most as long as the maximum dorsoventral diameter of metafemur. Mandibles striate; entire body including propodeal declivity densely punctate; on sides of pronotum punctures aligned in diffuse lines, appearing striate; punctures on antennae, legs, and abdominal segment IV finer than on rest of body, abdominal segments V–VII very superficially punctured and shiny. Body color uniformly orange brown to reddish brown, vertex of head slightly darker, frontal furrow conspicuously darker than surrounding cephalic dorsum, legs, antennal funiculus, and abdominal segments V–VII yellowish brown.

Etymology.

The species epithet is a patronym in honor of the Chinese botanist Prof. Keping Ma and his efforts in establishing the BEF-China project and promoting biodiversity research and nature conservation in China. All specimens of this species were collected in old-growth subtropical forest, an ecosystem Prof. Ma has investigated in detail.

Distribution and ecology.

Both specimens were collected in secondary mixed evergreen broadleaved forest of relatively advanced age, as indicated by the presence of large trees. The paratype was collected within the Gutianshan National Nature Reserve ( Yu et al. 2001, Bruelheide et al. 2011, Staab 2014), one of the larger remaining fragments of subtropical broadleaved forest in southeast China. The forest at this locality (the type locality is a similar but much smaller forest fragment) is on sloped land and rich in plant species; more than 250 woody species have been recorded on about 8000 ha. Approximately 50% of the woody species are deciduous but the tree layer is dominated by evergreen species including Castanopsis eyrei ( Fagaceae ) (Champ. ex Benth.) Tutch., Cyclobalanopsis glauca ( Fagaceae ) (Thunb.) Oerst., Machilus thunbergii ( Lauraceae ) Sieb. et Zucc., and Schima superba ( Theaceae ) Gardn. et Champ. No direct observations of biology and natural history are available for P. kepingmai .

Taxonomic notes.

Proceratium kepingmai is the largest (WL 1.14-1.24) member of the P. itoi clade and has, even for eye-bearing Proceratium , very minute eyes (OI 2-3). From each of the species in the clade with very similar body proportions (particularly indices) that also have erect hairs on the dorsal surface of the body ( P. itoi , P. longmenense , P. malesianum , P. bruelheidei ; no erect hairs, only dense pubescence in P. williamsi , P. zhaoi ) it can safely be separated by one or more characters. In P. kepingmai the posterodorsal corner of the propodeum is angular (rounded in P. itoi and P. malesianum ), which is also the case for P. longmenense and P. bruelheidei . However, P. longmenense lacks erect hairs on the scape (at least some erect hairs present in P. kepingmai and P. bruelheidei ), has a relatively narrower head (CI 85) with longer scapes (SI 68) (CI 92-93 and SI 60-62 in P. kepingmai ), and frontal carinae that touch each other at their anteriormost level (clearly separated in P. kepingmai and P. bruelheidei ). With P. bruelheidei , the most similar species, P. kepingmai also shares the broad frontal carinae that have large lamellae and are conspicuously extended laterally above the antennal insertions (not extended and narrower in P. longmenense ). In contrast, P. kepingmai differs from P. bruelheidei by the shape of the head in full-face view that has convex sides, which are broadest at the level of the eyes and narrow weakly anteriorly and more strongly posteriorly towards to almost straight vertex (sides straight, not narrowing anteriorly and vertex convex in P. bruelheidei ), the densely punctured and mostly opaque propodeal declivity (sparsely and superficially punctured and very shiny in P. bruelheidei ), the conspicuous frontal furrow that is darker than the rest of the surrounding anterior cephalic dorsum (inconspicuous and of same color in P. bruelheidei ), the posterior face of petiolar node in profile steeper than the anterior face of the node and about half as long as the anterior face (posterior face as steep as anterior face and less than half as long in P. bruelheidei ), the apex of the petiolar node that is clearly broader than long in dorsal view (less broad than long in P. bruelheidei ), and relatively fewer and shorter erect hairs (see P. bruelheidei for details).

Variation.

Apart from the small difference in body size (WL 1.14 vs. 1.24) there is no observable variation between the two specimens.