Strumigenys anhdaoae, 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 : 15-18

Strumigenys anhdaoae sp. nov.

urn:lsid:zoobank.org:act:08768AE0-F425-4D89-9CE4-EAC1AF33619D

Figs 3–4 ; Tables 2–3

Diagnosis

Strumigenys anhdaoae sp. nov. can be distinguished from other species in the S. koningsbergeri -group by a combination of the following characters: preapical tooth extremely reduced; in profile view, erect seta absent on pronotal dorsum; pronotal humeral seta present; side of propodeum densely areolate to areolate-rugulose; propodeal spines subtended by broad lamella; without visible femoral gland on hind leg in workers; HL 0.65–0.69, SI 50–56.

Etymology

The species is named after Dr Thi Anh Dao Tran, whose tremendous help and warm welcome during one of our journeys to Vietnam was invaluable and has led to the discovery of the species. The name was created by adding the singular Latin genitive case suffix -ae to the given name of a female person.

Type material

Holotype worker ( Fig. 3 )

VIETNAM • Đắk Nông Province , Nam Nung Reserve, Site 73; 12.23113° N, 107.83153° E; 907 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; mature forest; LKCNHM ANTWEB1011855 (collection code IBBL NN-S73-sp21).

Paratype workers

VIETNAM • 10 workers; same collection data as for holotype; HKBM ANTWEB1011857 to ANTWEB1011865 , ANTWEB1011856 (collection code IBBL NN-S73-sp21) .

Paratype queens ( Fig. 4 )

VIETNAM • 2 dealate queens; same collection data as for holotype; IBBL ANTWEB1011854 , ANTWEB1011866 (collection code IBBL NN-S73-sp21) .

Additional material examined

VIETNAM – Đắk Nông Province • 13 workers, 1 queen; Nam Nung Reserve ; 12.20462° N, 107.75243° E; 885 m a.s.l.; 9 Jun. 2018; IBBL members legs.; Winkler; IBBL ANTWEB1011870 • 5 workers; Nam Nung Reserve ; 12.19073° N, 107.75925° E; 883 m a.s.l.; 9 Jun. 2018; IBBL members legs.; Winkler; IBBL ANTWEB1011871 • 1 worker; Nam Nung Reserve ; 12.18893° N, 107.76046° E; 890 m a.s.l.; 9 Jun. 2018; IBBL members leg.; Winkler; IBBL • 1 worker; same collection data as for preceding • 27 workers, 2 queens; Nam Nung Reserve ; 12.18737° N, 107.76132° E; 888 m a.s.l.; 9 Jun. 2018; IBBL members leg.; Winkler; IBBL • 8 workers; same collection data as for preceding • 1 worker; Nam Nung Reserve ; 12.20555° N, 107.75305° E; 886 m a.s.l.; 9 Jun. 2018; IBBL members leg.; Winkler; IBBL • 1 worker; Nam Nung Reserve ; 12.20579° N, 107.75476° E; 882 m a.s.l.; 9 Jun. 2018; IBBL members leg.; Winkler; IBBL • 39 workers; Nam Nung Reserve ; 12.19245° N, 107.75954° E; 892 m a.s.l.; 9 Jun. 2018; IBBL members leg.; Winkler; IBBL • 1 worker; Nam Nung Reserve ; 12.16998° N, 107.7696° E; 897 m a.s.l.; 10 Jun. 2018; IBBL members leg.; Winkler; IBBL • 2 workers; Nam Nung Reserve ; 12.22927° N, 107.83662° E; 805 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; IBBL • 4 workers; Nam Nung Reserve ; 12.23077° N, 107.83045° E; 911 m a.s.l.; 12 Jun. 2018; IBBL members legs.; Winkler; IBBL ANTWEB1011867 • 1 worker; same collection data as for preceding; IBBL ANTWEB1011868 • 15 workers, 1 queen; Nam Nung Reserve ; 12.23113° N, 107.83153° E; 907 m a.s.l.; 12 Jun. 2018; IBBL members legs.; Winkler; IBBL ANTWEB1011869 .

Measurements

Holotype worker

TL 2.6, HL 0.69, HW 0.62, MandL 0.31, SL 0.34, EL 0.054, PW 0.30, ML 0.65, PL 0.26, PH 0.13, DPW 0.12, PPL 0.12, GL 0.59, CI 91, MI 45, SI 55, OI 9, LPI 50, DPI 45.

Paratype workers

TL 2.4–2.6, HL 0.65–0.68, HW 0.58–0.61, MandL 0.30–0.31, SL 0.30–0.34, EL 0.048 –0.057, PW 0.26– 0.29, ML 0.59–0.64, PL 0.23–0.28, PH 0.11–0.13, DPW 0.10–0.13, PPL 0.11–0.17, GL 0.51–0.58, CI 87–93, MI 44–48, SI 50–56, OI 8–10, LPI 43–51, DPI 41–49 (n=10).

Paratype queens

TL 2.8–3.0, HL 0.67–0.69, HW 0.63–0.65, MandL 0.31–0.33, SL 0.32–0.35, EL 0.106 –0.113, PW 0.36– 0.38, ML 0.75–0.77, PL 0.29–0.31, PH 0.14–0.15, DPW 0.13–0.15, PPL 0.11–0.13, GL 0.69–0.76, CI 94, MI 47–48, SI 51–54, OI 16–18, LPI 47–50, DPI 46–48 (n=2).

Worker description

HEAD. In full-face view, occipital margin deeply, evenly concave; occipital corners well developed, forming continuous contour with lateral margin of occipital lobe, not angular; anterior clypeal margin broadly concave. Mandible with mostly straight outer margin; inner margin also mostly straight, subparallel to outer margin (slightly diverging), with distal one-fifth to one-quarter of mandible strongly concave with respect to previous line; extremely reduced preapical tooth (or rather remnant of one) present, which is merely small bulge from contour of mandible, located at proximal end of concave portion of inner margin ( Fig. 4B ). Antennal scape subcylindrical; apical antennomere not constricted basally. In profile view, transverse impression across vertex weakly developed; ventrolateral margin of head in front of eye deeply concave; eye with four ommatidia in diameter.

MESOSOMA. In profile view, promesonotal dorsum broadly convex, with slight depression at mesonotum; pronotum weakly marginated dorsolaterally. In dorsal view, lateral margins of pronotum evenly convex. Propodeal teeth triangular, armed at slightly upward angle, subtended on each side by broad lamella with concave posterior margin that broadens basally into rounded convex propodeal lobe. Metapleural gland bulla well-developed. Femoral gland not visible in dorsal view.

METASOMA. In profile view, petiolar node high; petiolar peduncle not grading evenly into node, and slightly longer than node, around 1.1–1.2 times as long; petiolar node with differentiated anterior face. In dorsal view, petiolar node broader than long, around 1.3–1.5 times as long; disc of postpetiole broader than long, around two 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 and just reaching midpoint of node; in dorsal view, processes present along lateral and posterior margins of petiolar node, and surrounding disc of postpetiole, thicker along posterior margin than on lateral and anterior margins.

PILOSITY. In full-face view, cephalic and clypeal dorsum sparsely with appressed, apically-acute setae pointed in random directions; mandibular dorsum with appressed short fine setae. Surface of scape covered with appressed setae; progressively finer setae densely covering funiculus. Lateral margin of occipital lobe, upper scrobe margin, lateral and anterior clypeal margins with decumbent shoehorn-shaped to narrowly spoon-shaped setae; leading edge of scape with similar, apically-directed setae. Apicoscrobal seta short, stout, slightly curved to straight, slightly longer than other setae on upper scrobe margin. In dorsal view, dorsum of promesonotum and petiolar node sparsely covered with short, apically-acute appressed setae. Pronotal humeral seta weakly remiform and very slightly curved. In profile view, stout to weakly remiform erect setae present as single row of four setae along occipital margin (slightly curved), on mesonotal dorsum in a pair, and sparsely across gastral tergites; similar but decumbent setae present on disc of postpetiole in a pair; setae on gaster markedly longer than those on other parts of body; ventral surface of head with decumbent setae; gastral sternites densely with fine suberect to decumbent setae. Hairwheel present at mesopleural excavation. Surfaces of femora, tibiae and basitarsi with short, apically-acute appressed setae only.

SCULPTURE. Surface of head (including antennal scrobe), antennae, mesosoma, legs and petiole densely areolate to areolate-rugulose, except for katepisternum, which is mostly smooth and shining with vestiges of sculpture around margins. Mandibles with sparse weak punctate sculpture and weakly areolate basally, but otherwise mostly smooth. Disc of postpetiole mostly smooth and shining. Basigastral costulae short, around one fourth in length of first gastral tergite; rest of gaster smooth and shining.

Queen description

Similar in all points to the worker caste except for the reproductive caste morphological characters (presence of 3 ocelli, enlarged eyes and thorax), and the following: in profile view, promesonotal dorsum with numerous setae, a mix of simple, stout and weakly remiform in forms, ranging from decumbent, suberect to erect; anepisternum mostly smooth; femoral glands visible on all legs in dorsal view, small; petiolar peduncle does not grade evenly into node but anterior face of petiolar node much less distinctive than in worker caste.

Comments

Strumigenys anhdaoae sp. nov. is a member of the koningsbergeri -complex in the S. koningsbergeri - group and shares all its characters ( Bolton 2000). It does not belong to the ebbae -complex as the preapical tooth is absent, and the remnant of the tooth is not at a right-angle to the long axis of the mandible.

Strumigenys anhdaoae sp. nov. can be distinguished from all other members of the koningsbergeri - complex by its extremely reduced preapical tooth, which is even smaller than a denticle; this remnant of the preapical tooth is merely a small bulge along the contour of the mandible, and is only observable under high-magnification.

Aside from Strumigenys anhdaoae sp. nov., there are nine other species in the koningsbergeri -complex ( S. amasara Bolton, 2000 , S. blanda Bolton, 2000 , S. ignota Bolton, 2000 , S. koningsbergeri Forel, 1905 , S. offina Bolton, 2000 , S. perturba Bolton, 2000 , S. seynoka Bolton, 2000 , S. strygax Bolton, 2000 and S. vertigosa Bolton, 2000 ) that also lack erect setae on the pronotal dorsum in profile ( Table 3 ). Strumigenys anhdaoae lacks a visible femoral gland on the hind leg in workers (unlike S. amasara , S. ignota , S. perturba or S. seynoka ); a pronotal humeral seta is present (unlike S. offina ); the side of the propodeum is densely areolate to areolate-rugulose (instead of entirely unsculptured as in S. koningsbergeri or S. strygax ); the propodeal lamellae are broad (instead of narrow as in S. blanda or S. vertigosa ). Strumigenys anhdaoae does not have the characteristic head shape of S. koningsbergeri . It is also a smaller species (HL 0.65–0.69, HW 0.58–0.62) than S. blanda (HL 0.82–0.96, HW 0.70– 0.82) or S. perturba (HL 0.81–0.91, HW 0.69–0.78), and has a relatively shorter scape (SI 50–56) than S. vertigosa (SI 65–69).

Geographic range

Vietnam (Đắk Nông).

Ecology

Collected in secondary and mature forest, and rarely in rubber plantation at elevations from 805 to 911 m.

Figures

Fig. 3. Holotype worker (ANTWEB1011855) of Strumigenys anhdaoae sp. nov. A. Full-face view. B. Profile view. C. Dorsal view.

Fig. 4. Paratype queen (ANTWEB1011854) of Strumigenys anhdaoae sp. nov. A. Full-face view. B. Reduced preapical tooth (red arrow) close-up in full-face view. C. Profile view. D. Dorsal view.