Tetramorium humbloti Forel, 1891

Garcia, Francisco Hita & Fisher, Brian L., 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region — taxonomy of the T. bessonii, T. bonibony, T. dysalum, T. marginatum, T. tsingy, and T. weitzeckeri species groups, Zootaxa 3365, pp. 1-123 : 118-120

Tetramorium humbloti Forel, 1891

( Figs 164, 165, 166 )

Tetramorium (Xiphomyrmex) humbloti Forel, 1891:154 . Syntype workers, COMOROS, Grand Comoro Is., Ngasiya , (L. Humblot) ( MHNG: CASENT0101295 , CASENT0101296 ) [examined]. [Combination in Xiphomyrmex by Emery, 1899:285; in Tetramorium by Bolton, 1979:142 ].

Tetramorium (Xiphomyrmex) humbloti var. pembensis Forel, 1907:82 . Syntype queens and males, TANZANIA, Pemba Island, (Voeltzkow) ( MHNG) [examined]; syntype workers, TANZANIA, Arusha Chini , 1903 ( MHNG) [examined] . [Synonymy with T. humbloti by Bolton, 1980:228; by Hita Garcia et al., 2010:72; here confirmed].

Tetramorium (Xiphomyrmex) humbloti var. victoriensis Forel, 1913:120 . Syntype workers, ZIMBABWE, Victoria Falls, Zambezi River , 17.II.1912, (G. Arnold) ( MHNG) [examined] . [Synonymy with T. humbloti by Bolton, 1980:228; by Hita Garcia et al., 2010:72; here confirmed].

Diagnosis

The combination of 11-segmented antennae, highly reduced sculpture and pilosity, and strongly anteroposteriorly compressed, squamiform petiole and postpetiole distinguish T. humbloti from all other Tetramorium in the Malagasy region.

Description

HL 0.73–0.83 (0.77); HW 0.71–0.82 (0.74); SL 0.52–0.62 (0.57); EL 0.16–0.21 (0.18); PH 0.40–0.45 (0.42); PW 0.53–0.63 (0.56); WL 0.87–1.00 (0.91); PSL 0.24–0.32 (0.26); PTL 0.08–0.13 (0.10); PTH 0.32–0.39 (0.35); PTW 0.29–0.38 (0.32); PPL 0.16–0.21 (0.19); PPH 0.35–0.47 (0.38); PPW 0.34–0.42 (0.37); CI 92–99 (97); SI 73–83 (77); OI 21–27 (24); LMI 45–48 (46); DMI 59–65 (62); PSLI 29–39 (34); PeNI 51–62 (57); LPeI 25–40 (30); DPeI 261–367 (318); PpNI 60–75 (66); LPpI 44–57 (50); DPpI 183–219 (198); PPI 110–125 (115) (25 measured).

Head longer than wide to almost as long as wide (CI 92–99). Anterior clypeal margin with distinct median impression, sometimes shallow. Frontal carinae strongly developed, ending shortly before posterior head margin. Antennal scrobes narrow and shallow, posterior and ventral margins never differentiated, as long as frontal carinae and not reaching posterior head margin. Antennal scapes of short to moderate length, not reaching posterior margin of head (SI 73–83). Eyes generally of moderate size (OI 21–27). Mesosomal outline in profile convex, comparatively stout and high, dorsally transversely rounded, weakly marginate from lateral to dorsal mesosoma, metanotal groove weakly developed or absent. Propodeal spines long to very long (PSLI 29–39); propodeal lobes small, triangular, and acute. Petiolar node strongly squamiform and anteroposteriorly compressed, anterior and posterior faces parallel, antero- and posterodorsal margins distinct but rounded and at about same height; node in dorsal view strongly transverse, usually three times wider than long, rarely less wide (DPeI 261–367), in lateral view usually more than three times higher than long, rarely less (LPeI 25–40). Postpetiole strongly squamiform and anteroposteriorly compressed, in dorsal view approximately twice as wide as long (DPpI 183–219), in lateral view approximately twice as high as long (LPpI 44–57). Postpetiole in profile weakly less voluminous than petiolar node, in dorsal view between 1.1 to 1.3 times wider than petiolar node (PPI 110–125). Mandibles distinctly longitudinally striate. Clypeus irregularly rugose, mostly longitudinally, sometimes rugo-reticulate; median ruga sometimes developed. Generally most of head with longitudinal rugae, often irregularly developed or with crossmeshes, almost reaching posterior head margin, cephalic dorsum with eight to 12 rugae, head laterally more reticulate-rugose, ground sculpture very conspicuously reticulate-punctate. Most of lateral area of mesosoma reticulate-rugose or rugose with reticulate-punctate ground sculpture; dorsum of mesosoma, especially on pronotum, typically completely unsculptured, smooth and shiny, sometimes with weak superficial sculpture on pronotum, propodeal declivity completely unsculptured and shiny. Petiole, postpetiole and gaster completely unsculptured, smooth and shiny. Head generally with numerous fine, long, erect hairs; mesosoma, petiole, and postpetiole usually completely without hairs, rarely mesosoma with up to three pairs, and petiole and postpetiole with one to two pairs. First gastral tergite always without standing hairs. Mesosoma and gaster with comparatively widely spaced and short appressed pubescence. Colouration variable, from light reddish brown to dark brown, mandibles always of lighter colour; appendages often of lighter colour, gaster often darker than remaining body.

Notes

In the Malagasy region, T. humbloti is present on the islands of the Comoros, Mauritius, Mayotte, Nosy Be, and Madagascar. There, most sampling localities are close to the coast in northern Madagascar, although two are situated at the southeastern coast. It seems that the species is fairly flexible in its habitat requirements since it was encountered in rainforests, tropical dry forests, littoral rainforests, coastal dunes, coastal scrubs, woodlands, disturbed forests, but also in coffee plantations and other anthropogenic habitats. This is surprising because in Africa T. humbloti appears to prefer open savannah, woodland, and other natural open habitats.

As mentioned above, this species is not likely to be misidentified with any other Malagasy species due to the strongly squamiform condition of both waist segments. The situation is different in the Afrotropical region because several species in the T. weitzeckeri species complex are morphologically very close to T. humbloti . However, the whole T. weitzeckeri species group was recently revised by Hita Garcia et al. (2010), and this work provides identification tools to differentiate T. humbloti and its Afrotropical allied species.

Material examined

BOTSWANA: Kabulabula (Vernay-Lang); COMOROS: Anjouan, Bimbini, 12.19635 S, 44.23752 E, 5 m, coastal scrub, mangrove, 27.I.2009 (B.L. Fisher); Grande Comoro, no further data; Grand Comoro Is., Ngasiya (L. Humblot); Mohéli, Ouallah, 12.32717 S, 43.65952 E, 10 m, coastal scrub, 17.I.2009 (B.L. Fisher); Mohéli, Ouallah, 12.34045 S, 43.66801 E, 5 m, coastal sand, 21.I.2009 (B.L. Fisher); Mohéli, Lac Boundouni, 12.37915 S, 43.85165 E, 25 m, dry forest, 20.I.2009 (B.L. Fisher); MADAGASCAR: no location (Voeltzkow); 10 km S of Cap Este, 16.I.1990 (G.D. Alpert); Antsiranana, Ambondrobe, 41.1 km 175° Vohemar, 13.71533 S, 50.10167 E, 10 m, littoral rainforest, 30.XI.2004, (B.L. Fisher); Antsiranana, Androybesakalava, 3.52 km SW Ambanja, 13.70727 S, 48.43221 E, 22 m, coffee plantation, 11.IV.2008 (B.L. Fisher); Antsiranana, Anketrabe, 12.40611 S, 49.22194 E, 98 m, stomach contents Mantella viridis , 6.I.2005 (F. Andreone); Antsiranana, Forêt d'Ampondrabe, 26.3 km 10° NNE Daraina, 12.97 S, 49.7 E, 175 m, tropical dry forest, 10.XII.2003 (B.L. Fisher); Antsiranana, 7 km N Joffreville, 12.33333 S, 49.25 E, 360 m, in forest, 26.I.2001 (M.E. Irwin); Antsiranana, 7 km N Joffreville, 12.33333 S, 49.25 E, 360 m, in forest, 26.–29.I.2001 (I. Schlinger & R. Harin'Hala); Antsiranana, Parc National Montagne d'Ambre, 12.51444 S, 49.18139 E, 960 m, rainforest, 5.–21.IV.2001 (R. Harin'Hala); Antsiranana, Parc National Montagne d'Ambre, 12.52028 S, 49.17917 E, 1125 m, rainforest, 29.I.–4.III.2001 (R. Harin'Hala); Antsiranana, Parc National Montagne d'Ambre, 12.52028 S, 49.17917 E, 1125 m, rainforest, 14.–30.V..2001 (R. Harin'Hala); Antsiranana, Nosy Be airport, 13.3138 S, 48.31509 E, 25 m, urban/garden, 15.IV.2008 (B.L. Fisher); Antsiranana, Nosy Be, Réserve Naturelle Intégrale de Lokobe, 6.3 km 112° ESE Hellville, 13.41933 S, 48.33117 E, 30 m, rainforest, 19.–24.III. 2001 (B.L. Fisher, C. Griswold et al.); Antsiranana, Nosy Faly, Tafiambotry, 35.3 km N Ambanja, 13.3654 S, 48.48775 E, 7 m, littoral rainforest, 12.IV.2008 (B.L. Fisher); Antsiranana, Réserve Spéciale d'Ambre, 3.5 km 235° SW Sakaramy, 12.46889 S, 49.24217 E, 325 m, tropical dry forest, 26.–31.I.2001 (B.L. Fisher, C. Griswold et al.); Antsiranana, Sakalava Beach, 12.26278 S, 49.3975 E, 10 m, across sandy trail in dwarf litoral forest, 16.–31.V.2001 (R. Harin'Hala); Antsiranana, Sakalava Beach, 12.26278 S, 49.3975 E, 10 m, across sandy trail in dwarf litoral forest, 6.–20.VII.2001 (R. Harin'Hala); Antsiranana, 3 km W Sakalava Beach, 12.28617 S, 49.36667 E, 40 m, whites dunes in littoral forest, 19.III.–4.IV.2001 (I. Schlinger & R. Harin'Hala); Antsiranana, Sakaramy, 12.33333 S, 49.25 E, 360 m, low rainforest, 6.–27.I.2007 (R. Harin'Hala & M.E. Irwin); Antsiranana, Sakaramy, 12.33333 S, 49.25 E, 360 m, low rainforest, 30.I.–18.II.2007 (R. Harin'Hala & M.E. Irwin); Fianarantsoa, Farafangana, 22.81967 S, 47.83 E, 10 m, urban gardens, 25.IV.2006 (B.L. Fisher et al.); Fianarantsoa, Manakara, 22.14817 S, 48.02267 E, 10 m, urban gardens, coastal Casuarina equisetifolia , 25.IV.2006 (B.L. Fisher); Fianarantsoa, Parc National d'Isalo, Ambovo Springs, 29.3 km 4° N Ranohira, 22.298 S, 45.352 E, 990 m, 9.–14.II.2003 (B.L. Fisher); Mahajanga, Manerinerina, 76.6 km N Antsohihy, 14.10744 S, 48.11046 E, 247 m, disturbed forest, 11.IV.2008, (B.L. Fisher); Toamasina, Baie d 'Antongil; MAURITIUS: Ile aux Aigrettes, 20.419 S, 57.731 E, 1 m, coastal scrub, 28.V.2005 (B.L. Fisher); MAYOTTE: Mont Combani, 12.80632 S, 45.15314 E, 370 m, rainforest, 25.XI.2007 (B.L. Fisher); Reserve forestiére Sohoa, 12.81237 S, 45.10476 E, 10 m, coastal dry scrub, 1.XII.2007 (B.L. Fisher); Tanaraki, 12.75754 S, 45.0678 E, 10 m, coastal scrub, 26.XI.2007 (B.L. Fisher); Tsingoni, 12.783 S, 45.1 E, litter of shrubs on mangrove edge, 27.II.–4.III.1999 (R. Jocque & G. DeSmet); SOUTH AFRICA: no location (H. Swale); TANZANIA: Arusha Chini, 1903; Pemba Island (Voeltzkow); Arusha Chini, 1903; Boma Gombe, 1903 ( Katona ); Mkomazi Game Reserve, Ibaya, 3°58' S, 37°48' E, 8.XII.1995 (H.G. Robertson); Mt. Meru, 28.X.1957 (E.S. Ross & R.E. Leech); Pemba I. (Voeltzkow); Sotele, 29.XI.1989 (N.M. Varela); Zanzibar, 16.VIII.1989 (B. Löhr); ZAMBIA: 16° 49.4' S, 26° 55.0' E, savannah woodland, 280m, 9.VIII.1998 (B.L. Fisher); 16° 48.4' S, 26° 57.1' E, savannah woodland, 250m (B.L. Fisher); Lusaka, Leopard Hill, 12° 33.29' S, 30° 17.74' E, 1300 m, miombo woodland, 29.XI.–3.XII.2005, (B.L. Fisher); ZIMBABWE: Mazoe Estates, 3.XII.1987 (H.G. Robertson); Rusape, 12.III.1958, 1200 m (E.S. Ross & R.E. Leech); Sawmills, 12.VII.1929 (G. Arnold); Umtali, 12.VI.1924; Umtali, Melsetter, II.1969 (R. Mussard); Victoria Falls, Zambezi River, 17.II.1912 (G. Arnold); Victoria Falls, 2.XII.1914 (G. Arnold); Victoria Falls, 7.III.1969 (W.L. Brown).

Figures

FIGURES 164–166. T. humbloti—CASENT0059691 (April Nobile 2006). 164. Body in profile. 165. Body in dorsal view. 166. Head in full-face view.