Tetramorium dichroum Santschi, 1932

Mbanyana, Nokuthula, Garcia, Francisco Hita, Robertson, Hamish Gibson & Roux, Johannes Jacobus Le, 2018, A taxonomic revision of seed harvester ants of the Tetramorium solidum group (Hymenoptera: Formicidae) in southern Africa, European Journal of Taxonomy 454, pp. 1-59 : 19-21

Tetramorium dichroum Santschi, 1932

Figs 2A , 4I , 9 , 24

Tetramorium solidum st. dichroum Santschi, 1932: 388 .

Diagnosis

In the Tetramorium solidum -group, there are five species with abundant hairs covering the dorsal surfaces of the whole body, namely, T. rothschildi , T. peringueyi , T. dichroum , T. margueriteae sp. nov. and T. brigitteae sp. nov. Tetramorium rothschildi is easily separated from other species by having branched hairs. Tetramorium dichroum can be easily distinguished from T. peringueyi and T. margueriteae sp. nov. by the absence of erect hairs on the antennal scapes. Tetramorium dichroum and T. brigitteae sp. nov. can be distinguished on the basis of the spine length: in T. dichroum spines are long and acute (PSLI 10–16) ( Fig. 4I ), whereas T. brigitteae sp. nov. has very short propodeal teeth (PSLI 6) ( Fig. 4J ).

Material examined

Syntypes

SOUTH AFRICA: 3 pinned workers, Northern Cape, Kimberley, 1924, Power leg. ( NHMB: CASENT0915004 ; SAMC: SAM-ENT-0011758 ).

Other material

SOUTH AFRICA (40 pinned specimens): Orange Free State: Tussen Die Riviere , 30.295° S, 26.14° E, 30 Mar.–1 Apr. 1987, H.G. Robertson leg. (SAM-HYM-C000310); Springfontein, Hillside Farm , 30°09′ S, 25°46′ E, 28 Sep. 1995, H.Adie leg. ( SAM-HYM-HYM-C008451 ). – Northern Cape: Kortkop farm near Strydenburg, 30°09′ S, 23°44′ E, 17 Jun. 1995, ex pitfall trap, Karoo vegetation, B. Chambers leg. ( SAM-HYM-C008779 ); Tankwa Karoo National Park , 32.17430° S, 19.97382° E, 602 m a.s.l., 7 Jan. 2009, N. Mbanyana and H.G. Robertson leg. (SAM-HYM-C023307); Melton Wold , 31.46189° S, 22.72417° E, 1331 m a.s.l., 9 Jan. 2009, N. Mbanyana and H.G. Robertson leg. ( SAM-HYM-C024387 ). – Eastern Cape: Cookhouse, 26 Jul. 1944, Agricultural Research Institute – Pretoria leg. ( SAM- HYM-C011579); Oviston , dolerite koppie, 21 Nov. 1988, W.R.J. Dean leg. (SAM-HYM-C001484); Kudu Reserve in Great Fish River , 33°7′42″ S, 26°41′32″ E, Grassland , 25–30 Apr. 2005, T. Jordan leg. ( SAM-HYM-C018977 ). – Western Cape: Molenrivier, 3 Feb. 1959, A. Boonzaaier leg. ( SAM- HYM-C019203); Klein Pakhuis, 32.14398° S, 19.05645° E, 506 m a.s.l., 10 Sep. 2009, P. Hawkes and J. Fisher leg. ( SAM-HYM-C024390 ); Cederberg Wilderness Area, Wupperthal , Hiking trail between Sneeukop Hut and Wupperthal site 3, 32.31096° S, 19.17055° E, 934 m a.s.l., 11 Oct. 2002, Fynbos , pitfall trap, A. Botes leg. (SAM-HYM-C024966).

ZAMBIA (4 pinned specimens): Northern Province, Luangwa National Park, 13.1667° S, 31.5° E, 500 m a.s.l., hand collected, 1 Jan. 2005, R. van den Elzen leg. ( BMNH: CASENT0746318 to CASENT0746321 ).

Measurements (worker N =11)

HL 0.934 –1.023 (0.987); HW 0.944 –1.072 (1.003); SL 0.659 –0.747 (0.703); EL 0.216 –0.246 (0.237); PH 0.393 –0.521 (0.451); PW 0.590 –0.669 (0.638); WL 0.924 –1.121 (1.015); PSL 0.098 –0.157 (0.136); PTH 0.315 –0.364 (0.341); PTL 0.275 –0.354 (0.325); PTW 0.315 –0.374 (0.343); PPH 0.315 –0.491 (0.438); PPL 0.246 –0.285 (0.267); PPW 0.382 –0.457 (0.415); OI 23–25 (24); CI 100–105 (102); SI 66–73 (70); DMI 59–70 (63); LMI 39–52 (45); PSLI 10–16 (14); PeNI 50–57 (54); LPeI 85–100 (95); DPeI 99–114 (106); PpNI 61–70 (65); LPpI 50–80 (62); DPpI 144–186 (156); PPI 115–128 (121).

Distribution

Tetramorium dichroum has been recorded from South Africa (Eastern Cape Province, southern parts of the Free State, Northern Cape and Western Cape Provinces) and Zambia. This species occurs in Drakensberg Montane Grasslands, Kalahari Xeric Savanna, Montane Fynbos and Renosterveld, Nama Karoo, Succulent Karoo, Zambezian and Mopane Woodlands.

Figures

Fig. 2. Body in profile showing pilosity and pubescence. A. T. dichroum Santschi, 1932 (CASENT0746320). B. T. peringueyi Arnold, 1926 (CASENT0250873). C. T. rothschildi (Forel, 1907) (CASENT0764434). D. T. clunum Forel, 1913 (CASENT0764600). E. T. galoanasum Santschi, 1910 (CASENT0915015 – Antweb, William Ericson). F. T. setuliferum Emery, 1895 (MCZ_ENT00512567). G. T. glabratum Stitz, 1923 (SAM-HYM-C024395). H. T. rufescens Stitz, 1923 (CASENT0250852). I. T. solidum Emery, 1886 (CASENT0250960).

Fig. 4. A–B. Mesosoma in dorsal view. A. T. signatum Emery, 1895 (SAM-HYM-C020573). B. T. glabratum Stitz, 1923 (SAM-HYM-C024395). C–D. Antennal scape in frontal view. C. T. aisha Mbanyana, Robertson & Hita Garcia sp. nov. (CASENT0250969). D. T. peringueyi Arnold, 1926 (SAM-HYM-C026796). E–F. Mesosoma in dorsal view. E. T. peringueyi (CASENT0250873). F. T. margueriteae Mbanyana, Robertson & Hita Garcia sp. nov. (SAM-NC07-012). G–H. Body in profile. G. T. peringueyi (CASENT0250873). H. T. margueriteae sp. nov. (SAM-HYM-C019839). I–L. Mesosoma in profile. I. T. dichroum Santschi, 1932 (CASENT0746320). J. T. brigitteae Mbanyana, Robertson&HitaGarciasp.nov.(SAM-HYM-C027040).K.T.solidumEmery, 1886(CASENT0250960). L. T. aisha sp. nov. (CASENT0250969).

Fig. 9. Tetramorium dichroum Santschi, 1932 (CASENT0746320). A. Body in profile. B. Body in dorsal view. C. Head in full-face view.

Fig. 24. Map showing the distribution of species in the Tetramorium solidum group.