Strumigenys claviseta, Tang & Guénard, 2023

Tang, Kit Lam & Guénard, Benoit, 2023, Further additions to the knowledge of Strumigenys (Formicidae: Myrmicinae) within South East Asia, with the descriptions of 20 new species, European Journal of Taxonomy 907, pp. 1-144 : 23-27

Strumigenys claviseta sp. nov.

urn:lsid:zoobank.org:act:51D223D7-3694-4627-AEF8-8FA8031DFE85

Figs 6–7 ; Tables 2 , 4

Diagnosis

Strumigenys claviseta sp. nov. can be distinguished from other species in the S. rostrata -group by a combination of the following characters: cephalic dorsum with appressed obovate setae; eye reduced to one ommatidium; pronotal humeral seta long and claviform; in profile view, near occipital margin with two claviform erect setae; mesonotal dorsum, petiolar node and first gastral tergite with similar setae; entire surface of mesosoma smooth and shinning except for mesonotal dorsum, which is areolate.

Etymology

The species is named after its club-like erect setae. The name was created by combining the prefix ‘ clavi ’ (meaning ‘club-shaped’) with the nominative singular of the Latin noun ‘ seta ’ (meaning ‘bristle’).

Type material

Holotype worker ( Fig. 6 )

VIETNAM • Đồng Nai Province , Cat Tien National Park, Site 36-2; 11.37623° N, 107.50349° E; 175 m a.s.l.; 7 Jun. 2018; IBBL members leg.; Winkler, 4 corners; rubber plantation; LKCNHM ANTWEB1011993 (collection code IBBL CT-S36-ST-sp02).

Paratype workers

VIETNAM • 6 workers; same collection data as for holotype; HKBM ANTWEB1011956 , ANTWEB1011988 to ANTWEB1011992 (collection code IBBL CT-S36-ST-sp02) .

Paratype queen ( Fig. 7 )

VIETNAM • 1 dealate queen; Đồng Nai Province , Cat Tien National Park, Site 37; 11.37042° N, 107.50924° E; 175 m a.s.l.; 7 Jun. 2018; IBBL members leg.; Winkler, 4 corners; rubber plantation; LKCNHM ANTWEB1011954 (collection code IBBL CT-S37-ST-sp02) .

Measurements

Holotype worker

TL 2.1, HL 0.53, HW 0.39, MandL 0.11, SL 0.28, EL 0.023, PW 0.23, ML 0.53, PL 0.25, PH 0.13, DPW 0.12, PPL 0.16, GL 0.50, CI 74, MI 20, SI 72, OI 6, LPI 51, DPI 48.

Paratype workers

TL 2.0–2.1, HL 0.51–0.55, HW 0.38–0.40, MandL 0.10, SL 0.27–0.30, EL 0.020 –0.030, PW 0.21–0.23, ML 0.51–0.57, PL 0.24–0.27, PH 0.13–0.14, DPW 0.12–0.13, PPL 0.13–0.16, GL 0.49–0.55, CI 72–75, MI 18–20, SI 71–77, OI 5–8, LPI 51–56, DPI 46–52 (n =6).

Paratype queen

TL 2.4, HL 0.56, HW 0.43, MandL 0.13, SL 0.30, EL 0.117, PW 0.28, ML 0.63, PL 0.30, PH 0.17, DPW 0.16, PPL 0.17, GL 0.66, CI 77, MI 23, SI 69, OI 27, LPI 56, DPI 54 (n= 1).

Worker description

HEAD. In full-face view, occipital margin broadly concave; occipital corners well developed. Anterior clypeal margin broadly convex, with moderately-rounded anterolateral angle; posterior clypeal margin well-defined, converged at midpoint to form right angle (or just slightly smaller than right angle); preocular lamina wide. Scapes dorsoventrally flattened, converging anteriorly to form flange at leading edge; trailing edge shallowly concave. Mandibles in full-face view elongated-triangular; masticatory margins engaged across entire length, without diastema or gap between mandibles. Eye reduced to only one ommatidium.

DENTITION ( Fig. 6B–C ). Principal dental row with five large teeth follows by two smaller teeth, first three teeth subequal in size, fourth tooth reduced, fifth tooth slightly smaller than first three teeth, all triangular except for fourth one; seventh tooth slightly longer than sixth tooth, both reduced; apex of mandible at down curvature, in anterior view, with series of four minute denticles, terminating in small apical tooth. Total dental count of 12.

MESOSOMA. In profile view, pronotum broadly, weakly convex, rest of mesosoma more or less flat; pronotum not marginated dorsolaterally. In dorsal view, lateral margins of pronotum evenly convex. Propodeal spines short, broadly triangular, subtended on each side by broad lamella with weakly convex posterior margin slightly narrowing basally into rounded convex propodeal lobe. Metapleural gland bulla well developed.

METASOMA. In profile view, petiolar node high; petiolar peduncle not grading evenly into node, and longer than node, around 1.3–1.4 times as long; petiolar node with differentiated anterior face, subequal in length to posterior face. In dorsal view, petiolar node broader than long, around 1.4–1.6 times as long; disc of postpetiole broader than long, around 1.6–1.8 times as long. Areolate processes (spongiform tissues) present on both petiole and postpetiole; ventral lobes of petiole and postpetiole extensive; lateral lobe of petiole merely a flap at posterolateral angle of node in profile; in dorsal view, processes present along lateral and posterior margins of petiolar node, and surrounding disc of postpetiole, thicker along lateral and posterior margins than on anterior margin.

PILOSITY. In full-face view, cephalic dorsum sparsely with appressed obovate setae, notably with one transverse row of such setae around level of antennal insertions; clypeal dorsum with small appressed oblanceolate setae; mandibular dorsum with appressed fine setae. Surface of scape sparsely with small appressed oblanceolate to subspatulate setae; funiculus densely covered with short fine setae. Laterally-projecting seta absent; lateral margin of occipital lobe with appressed setae; lateral and anterior clypeal margins with small spoon-shaped setae, medially-directed; leading edge of scape with row of projecting spoon-shaped setae, all curved except for third basalmost seta, posited on subbasal angle, mostly straight and longest of all; three setae immediately following straight seta basally-directed; all other setae apically-directed. In dorsal view, dorsum of pronotum close to anterior margin, mesonotum, petiolar node and disc of postpetiole with small appressed subspatulate to obovate setae. Pronotal humeral seta long and claviform, slightly curved ( Fig. 6D ). In profile view, immediately in front of occipital margin near midline with a pair of long, slightly curved claviform erect setae; similar setae also present on mesonotum in a pair, on petiolar node in a pair, and sparsely across first gastral tergite; second and third gastral tergites with smaller weakly claviform to remiform erect setae; gastral sternites with suberect to decumbent setae; ventral surface of head with appressed setae. Hairwheel present at the mesopleural excavation. Surfaces of femora, tibiae and basitarsi with appressed subspatulate to obovate setae; surfaces of middle and hind basitarsi without any projecting erect seta.

SCULPTURE. Surface of head (including antennal scrobe), antennae and legs areolate. Entire surface of mesosoma smooth and shinning, except for mesonotal dorsum, weakly areolate. Dorsum of petiolar node and disc of postpetiole mostly smooth and shining. Basigastral costulae short, around one fifth in length of first gastral tergite; rest of gaster smooth and shining.

Queen description

Similar in all points to worker caste except for reproductive caste morphological characters (presence of 3 ocelli, enlarged eyes and thorax), and following: in profile view, in front of occipital margin with two pairs of claviform erect setae instead of one, additional pair situated around ocelli; mesosomal dorsum with numerous claviform erect setae; claviform erect setae on gastral tergites restricted to anterior portion of first gastral tergite only, remaining erect setae on gaster remiform to weakly remiform; mesosomal dorsum densely areolate; side of mesosoma with vestiges of sculpture around the margins.

Comments

Strumigenys claviseta sp. nov. is a member of the S. rostrata -group and shares all its characters ( Bolton 2000). It cannot be confidently assigned to either the fautrix -complex or rostrata -complex. Strumigenys claviseta has wide preocular laminae, similar to species of the rostrata -complex, but also has well-developed occipital lobes, similar to species of the fautrix -complex. The roundness of the anterolateral angles of the clypeus in S. claviseta falls between the norm of the two species complexes.

Strumigenys claviseta sp. nov. can be distinguished from other Oriental and Sino-Japanese species from the species group ( S. atropos ( Bolton, 2000) , S. emeswangi ( Bolton, 2000) , S. incerta (Brown, 1949) , S. nepalensis De Andrade, 1994 , S. jaitrongi sp. nov., S. rostrataeformis (Brown, 1949) , S. subterranea Brassard et al., 2020 ) by the following characters( Table 4 ): antennae 6-segmented (instead of 4-segmented as in S. nepalensis ); mandibles without gap between them (unlike S. jaitrongi or S. subterranea ); eyes greatly reduced (unlike S. emeswangi , S. incerta , S. nepalensis or S. rostrataeformis ); in profile view, cephalic dorsum of worker has two erect claviform setae (instead of four such setae as in S. jaitrongi , remiform as in S. atropos or S. subterranea , or completely absent as in other species); pronotal dorsum completely smooth and shining (unlike S. nepalensis , S. emeswangi , S. incerta or S. rostrataeformis ); mesonotal dorsum weakly areolate (instead of smooth and shining as in S. atropos ); pronotal humeral seta distinctly claviform (instead of stout as in S. atropos or S. nepalensis , or remiform as in S. rostrataeformis , or flagellate as in other species). Unlike all other species, the pilosity on the first gastral tergite of S. claviseta sp. nov. consists of claviform erect setae only.

Geographic range

Vietnam (Đồng Nai).

Ecology

Collected in rubber plantation at an elevation of 175 m.

Figures

Fig. 6. Type specimens of Strumigenys claviseta sp. nov.A, E–F. Holotype worker (ANTWEB1011993). B–D. Paratype worker (ANTWEB1011956). A. Full-face view. B–C. Mandible close-ups. D. Promesonotum close-up in dorsal view. E. Profile view. F. Dorsal view.

Fig. 7. Paratype queen (ANTWEB1011954) of Strumigenys claviseta sp. nov. A. Full-face view. B. Profile view. C. Dorsal view.