Aenictus steindachneri Mayr, 1901

Gómez, Kiko, 2022, A revision of the Afrotropical species of the Dorylinae ant genus Aenictus (Hymenoptera: Formicidae) based on the worker caste, Belgian Journal of Entomology 124, pp. 1-86 : 57-58

Aenictus steindachneri Mayr, 1901

( Figs 39 A–D , 40 )

Aenictus steindachneri MAYR, 1901: 2 (w.)

Syntypes, SOUTH AFRICA: Orange [ CASENT0911440 ] (4w) NHMB [Examined]; Syntype, SOUTH AFRICA: Free State, Reddesburg (1w) [ CASENT0919642 ] NMHW: Coll. Mayr [Examined] ; Syntypes, SOUTH AFRICA: Free State, Orange ( Arnold ) (6w) MHNG: Coll. Forel [Examined].

DIAGNOSIS. This species can be separated from the rest of the group as it presents a quite dense white pubescence directed backwards at the meso and especially at the metapleurae. The other species may present some isolated small setae, but never becoming pubescent in appearance. It also presents the most developed propodeal process of the four species in this complex.

Its general shape, size and colour might resemble A. rotundatus , but can be separated due to its shorter scapes (SIL>60 for rotundatus ) and cited pubescence. There is a series of 8 workers at MNHW from Reddesburg, identified by E. Mayr as types for “ A. rotundatus laevigatus ”, probably part of the type series for A. steindachneri, but not labelled as such.

DESCRIPTION ( Fig. 39 A–D ). WORKER. HL: 0.59 [0.43-0.74]; HW: 0.51 [0.36-0.65]; SL: 0.31 [0.20-0.38]; WL: 0.82 [0.56-1.03]; PL: 0.20 [0.14-0.25]; PH: 0.17 [0.12-0.20]; PPL: 0.17 [0.11- 0.22]; PPH: 0.14 [0.10-0.16]; CS: 0.55 [0.39-0.70]; CI: 86 [79-93]; SIL: 52 [46-57]; SIW: 60 [53-66]; WL/HW: 159 [147-177]; PI: 122 [105-133]; PPI: 121 [100-138]; CSR: 176; (n=21).

Polymorphic (CSR>170). Scapes short, just reaching the median line of the head when laid back (SL/HL~0.55). Funicular segments wider than long, the apical about twice longer than wide. Head rectangular, longer than wide (CI~85), slightly widest at the middle. Occipital line straight. Mandibles with a long, sharp apical tooth and 5–7 smaller denticles, sometimes eroded seeming edentate. Frontal ridges present fused in the minor workers and touching each other in major workers.

Major workers with pro and mesonotum slightly convex, propodeum flat and slightly elevated in the major workers, with a discernible mesopropodeal suture and anterior sloping face; minima workers with flat mesosoma in profile, mesopropodeal suture absent, and all the spectrum in the middle. Transverse mesopleural groove not present. Mesometapleural suture present but very weak. Propodeal declivity weakly concave with propodeal ridges absent; a weak faint line can be present in major workers laterally.

Petiole with anterolateral ridges present, anterodorsal and dorsolateral ridges absent. Petiolar and postpetiolar domes low, rounded in lateral view, subrectangular, anteriorly vertical and posteriorly rounded. Subpetiolar process strongly developed, with a bulky elliptical process followed by a big triangular to elliptical lamellae oriented forward-downward, lamella becoming half the total process height.

All body surfaces smooth and shining except for mandibles with some feeble rugulae at the base and sometimes a small carina at its basal half not covering the whole mandibular length; meso and metapleurae from alutaceus to reticulate, spaces inside reticulation smooth; lateral sides of petiole and postpetiole from smooth to alutaceus. Overall colour bright yellow to yellow, punctate zones and sutures darker.

Decumbent to semierect white setae present, including head, scapes and legs. Dorsum of propodeum bare except for its anterior and posterior borders. The setae variable in length, the longest comparable to petiole height. Scapes and funiculus with decumbent to semierect pilosity, the longest setae on scape clearly longer than maximum scape width; meso and metapleurae covered with a dense white short pubescence directed backwards.

OTHER MATERIAL EXAMINED. SOUTH AFRICA: • Free State, Orange (por Koruwoiko') (2W) NHMB • Free State, Reddesburg (7 pins, 1w each; 1 pin 1w) NMHW (probably Syntypes, not labelled as such, see note above) • KwaZulu-Natal, Natal ( Havilland ) (2w) [ NHMUK012849268 ] BMNH. ZIMBABWE: • Bulawayo 01/01/1912 (Arnold, G.) (4w) [ NHMUK012849254 ] BMNH • same data (6w) [ NHMUK 012849261] BMNH.

DISTRIBUTION. Southern African, known from South Africa and Zimbabwe ( Fig. 40 ).

Figures

Fig. 39. Aenictus steindachneri, syntype (CASENT0919642). A, head, dorsal view. B, habitus, lateral view. C, mesosoma, petiole and postpetiole, lateral view. D, mesosoma, petiole and postpetiole, dorsal view.

Fig. 40. Distribution of A. steindachneri.