Tetramorium tenuinode Hita Garcia & Fisher

Hita Garcia, Francisco & Fisher, Brian L., 2014, The hyper-diverse ant genus Tetramorium Mayr (Hymenoptera, Formicidae) in the Malagasy region taxonomic revision of the T. naganum, T. plesiarum, T. schaufussii, and T. severini species groups, ZooKeys 413, pp. 1-170 : 74-78

Tetramorium tenuinode Hita Garcia & Fisher sp. n. Figs 24B, 25C, 26A, 26B, 39, 64

Type material.

Holotype, pinned worker, MADAGASCAR, Fianarantsoa, Parc National de Ranomafana, Vatoharanana River, 4.1 km 231° SW Ranomafana, 21.29°S, 47.43333°E, 1100 m, montane rainforest, sifted litter (leaf mold, rotten wood), collection code BLF08400, 27.-31.III.2003 (B.L. Fisher et al.) (CAS: CASENT0040115). Paratypes, 41 pinned workers with same data as holotype (CAS: CASENT0039644; CASENT0039646; CASENT0039651; CASENT0039655; CASENT0039660; CASENT0039664; CASENT0039668; CASENT0039671; CASENT0039673; CASENT0039737; CASENT0039739; CASENT0039745; CASENT0039749; CASENT0039750; CASENT0039754; CASENT0039759; CASENT0039761; CASENT0039809; CASENT0040000; CASENT0040020; CASENT0040023; CASENT0040035; CASENT0040036; CASENT0040090; CASENT0040092; CASENT0040096; CASENT0040099; CASENT0040105; CASENT0040106; CASENT0040112; CASENT0040123; CASENT0040181; CASENT0040279; CASENT0040284; CASENT0040285; CASENT0040293; CASENT0040296; CASENT0040304; CASENT0040306; CASENT0040311; CASENT0040317); and nine pinned workers with same data as holotype except collected ex rotten log and collection code BLF08488 (BMNH: CASENT0497623; CAS: CASENT0497621; MCZ: CASENT0497622).

Non-type material.

MADAGASCAR: Antsiranana, Forêt Ambanitaza, 26.1 km 347° Antalaha, 14.67933°S, 50.18367°E, 240 m, rainforest, 27.XI.1994 (B.L. Fisher); Antsiranana, 1 km W Andampibe, Cap Masoala, 15.69361°S, 50.18139°E, 125 m, lowland rainforest, 1.XII.1993 (G.D. Alpert); Fianarantsoa, 45 km S Ambalavao, 22.21667°S, 47.01667°E, 785 m, rainforest, 25.IX.1993 (B.L. Fisher); Fianarantsoa, 45 km S Ambalavao, 22.21667°S, 47.01667°E, 720 m, rainforest edge, 31.X.1993 (B.L. Fisher); Fianarantsoa, 2 km W Andrambovato, along river Tatamaly, 21.51167°S, 47.41°E, 1075 m, montane rainforest, 3.-5.VI.2005 (B.L. Fisher et al.); Fianarantsoa, Rés. Andringitra, 43 km S Ambalavao, 22.23333°S, 47°E, 825 m, rainforest, 5.X.1993 (B.L. Fisher); Fianarantsoa, R.S. Ivohibe, 7.5 km ENE Ivohibe, 22.47°S, 46.96°E, 900 m, rainforest, 7.-12.X.1997 (B.L. Fisher); Fianarantsoa, R.S. Ivohibe, 8.0 km E Ivohibe, 22.48333°S, 46.96833°E, 1200 m, montane rainforest, 15.-21.X.1997 (B.L. Fisher); Fianarantsoa, 9.0 km NE Ivohibe, 22.42667°S, 46.93833°E, 900 m, rainforest, 17.XI.1997 (B.L. Fisher); Fianarantsoa, Réserve Speciale Manombo 24.5 km 228° Farafangana, 23.01583°S, 47.719°E, 30 m, lowland rainforest, 20.IV.2006 (B.L. Fisher et al.); Fianarantsoa, Ranomafana Nat. Park, Maharira forest, 21°S, 47°E, 1190 m, montane forest, 11.X.1992 (E. Rajeriarison); Fianarantsoa, Parc National de Ranomafana, Vatoharanana River, 4.1 km 231° SW Ranomafana, 21.29°S, 47.43333°E, 1100 m, montane rainforest, 27.-31.III.2003 (B.L. Fisher et al.); Fianarantsoa, Forêt de Vevembe, 66.6 km 293° Farafangana, 22.791°S, 47.18183°E, 600 m, rainforest, transition to montane forest, 23.IV.2006 (B.L. Fisher et al.); Toamasina, Montagne d’Akirindro 7.6 km 341° NNW Ambinanitelo, 15.28833°S, 49.54833°E, 600 m, rainforest, 17.-21.III.2003 (B.L. Fisher et al.); Toamasina, 6.3 km S Ambanizana, Andranobe, 15.6813°S, 49.958°E, 25 m, rainforest, 14.XI.1993 (B.L. Fisher); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.77274°S, 49.26551°E, 450 m, rainforest, 20.-22.II.2010 (B.L. Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.7633°S, 49.26692°E, 520 m, rainforest, 22.-24.II.2010 (B.L. Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.81753°S, 49.29498°E, 360 m, rainforest, 25.-27.II.2010 (B.L. Fisher et al.); Toamasina, Forêt Ambatovy, 14.3 km 57° Moramanga, 18.85083°S, 48.32°E, 1075 m, montane rainforest, 21.III.2004 (Malagasy ant team); Toamasina, Ambatovy, 12.4 km NE Moramanga, 18.83937°S, 48.30842°E, 1080 m, montane rainforest, 4.-8.III.2007 (B.L. Fisher et al.); Toamasina, Analamay, 18.80623°S, 48.33707°E, 1068 m, montane rainforest, 21.III.2004 (Malagasy ant team); Toamasina, Corridor Forestier Analamay-Mantadia, Ambatoharanana, 18.80388°S, 48.40506°E, 1013 m, rainforest, 12.-19.XII.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.76087°S, 48.37128°E, 1044 m, rainforest, 23.-28.XI.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.77898°S, 48.36375°E, 918 m, rainforest, 23.-28.XI.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.76131°S, 48.36437°E, 983 m, rainforest, 26.XI.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Tsaravoniana, 18.76124°S, 48.42134°E, 939 m, rainforest, 2.-7.XII.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Tsaravoniana, 18.76465°S, 48.41938°E, 1039 m, rainforest, 2.-7.XII.2012 (B.L.Fisher et al.); Toamasina, Station Forestière Analamazaotra, Analamazaotra 1.3 km S Andasibe, 18.38466°S, 48.41271°E, 980 m, montane rainforest, 11.-13.XII.2007 (B.L. Fisher et al.); Toamasina, F.C. Andriantantely, 18.695°S, 48.81333°E, 530 m, rainforest, 4.-7.XII.1998 (H.J. Ratsirarson); Toamasina, Montagne d’Anjanaharibe, 18.0 km 21° NNE Ambinanitelo, 15.18833°S, 49.615°E, 470 m, rainforest, 8.-12.III.2003 (B.L. Fisher et al.); Toamasina, Ankerana, 18.40829°S, 48.82107°E, 750 m, rainforest, 21.-26.I.2012 (B.L. Fisher et al.); Toamasina, Ankerana, 18.4104°S, 48.8189°E, 855 m, rainforest, 22.-27.I.2012 (B.L. Fisher et al.); Toamasina, Reserve Betampona, Camp Vohitsivalana, 37.1 km 338° Toamasina, 17.88667°S, 49.2025°E, 520 m, rainforest, 1.-3.XII.2005 (B.L.Fisher et al.); Toamasina, Reserve Betampona, Camp Rendrirendry, 34.1 km 332° Toamasina, 17.924°S, 49.19967°E, 390 m, rainforest, 28.XI.2005 (B.L.Fisher et al.); Toamasina, F.C. Didy, 18.19833°S, 48.57833°E, 960 m, rainforest, 16.-23.XII.1998 (H.J. Ratsirarson); Toamasina, Parc National Mananara-Nord, 7.1 km 261° Antanambe, 16.455°S, 49.7875°E, 225 m, rainforest, 14.XI.2005 (B.L. Fisher et al.); Toamasina, 19 km ESE Maroantsetra, 15.48333°S, 49.9°E, 350 m, rainforest, 22.IV.1989 (P.S. Ward); Toamasina, 16 km S Moramanga, 19.08333°S, 48.23333°E, 950 m, rainforest, 18.XI.1990 (P.S. Ward); Toamasina, Moramanga, 18.94417°S, 48.23067°E, 922 m, urban/garden, 14.II.2007 (B.L. Fisher et al.); Toamasina, F.C. Sandranantitra, 18.04833°S, 49.09167°E, 450 m, rainforest, 18.-24.I.1999 (H.J. Ratsirarson); Toamasina, Parc National de Zahamena, Onibe River, 17.75908°S, 48.85468°E, 780 m, rainforest, 21.-23.II.2009 (B.L. Fisher et al.); Toamasina, Parc National de Zahamena, Tetezambatana forest, near junction of Nosivola and Manakambahiny rivers, 17.74298°S, 48.72936°E, 860 m, rainforest, 18.-19.II.2009 (B.L. Fisher et al.); Toliara, Rés. Andohahela, 10 km NW Enakara, 24.56667°S, 46.81667°E, 430 m, rainforest, 22.XI.1992 (B.L. Fisher); Toliara, Rés. Andohahela, 6 km SSW Eminiminy, 24.73333°S, 46.8°E, 330 m, rainforest, 4.II.1993 (G.D. Alpert & P.S. Ward); Toliara, Parc National d’Andohahela, Col du Sedro, 3.8 km 113° ESE Mahamavo, 37.6 km 341° NNW Tolagnaro, 24.76389°S, 46.75167°E, 900 m, montane rainforest, 21.-25.I.2002 (B.L. Fisher et al.); Toliara, Andohahela, 24.77639°S, 46.70528°E, 320 m, 9.XII.2007 (A. Ballerio); Toliara, Grand Lavasoa, 25.9 km W Tolagnaro, 25.08767°S, 46.749°E, 450 m, rainforest, 30.XI.-2.XII.2006 (B.L. Fisher et al.).

Diagnosis.

The following character set clearly distinguishes Tetramorium tenuinode from the remainder of the Tetramorium cognatum species complex: eyes relatively large (OI 25-27); antennal scapes very short (SI 66-70); frontal carinae well developed, noticeably raised, and approaching or ending at posterior head margin; petiolar node high rounded nodiform, in profile around 1.8 to 2.2 times higher than long (LPeI 45-54), in dorsal view around 1.3 to 1.4 times wider than long (DPeI 125-143); mesosoma with only two pairs of long, standing hairs, one on anterior pronotum and one on anterior mesonotum.

Worker measurements

(N=12). HL 0.62-0.75 (0.71); HW 0.58-0.70 (0.66); SL 0.40-0.47 (0.45); EL 0.16-0.18 (0.17); PH 0.30-0.36 (0.34); PW 0.42-0.54 (0.50); WL 0.76-0.94 (0.88); PSL 0.11-0.18 (0.14); PTL 0.13-0.17 (0.15); PTH 0.26-0.32 (0.30); PTW 0.16-0.21 (0.20); PPL 0.15-0.22 (0.20); PPH 0.25-0.32 (0.30); PPW 0.24-0.33 (0.30); CI 91-93 (92); SI 66-70 (68); OI 25-27 (26); DMI 55-59 (57); LMI 38-40 (39); PSLI 17-24 (20); PeNI 36-42 (39); LPeI 45-54 (49); DPeI 125-143 (133); PpNI 57-64 (61); LPpI 60-72 (67); DPpI 143-168 (153); PPI 148-167 (155).

Worker description.

Head longer than wide (CI 91-93); in full-face view posterior head margin weakly to moderately concave. Anterior clypeal margin with distinct median impression. Frontal carinae well developed, noticeably raised, diverging posteriorly, approaching or ending at posterior head margin. Antennal scrobes weakly developed, shallow and without clear and distinct posterior and ventral margins. Antennal scapes very short, not reaching posterior head margin (SI 66-70). Eyes relatively large (OI 25-27). Mesosomal outline in profile flat to weakly convex, moderately low and long (LMI 38-40), moderately marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove very weak to absent. Propodeal spines short to moderately long, usually elongate-triangular, and acute (PSLI 17-24), propodeal lobes short and triangular, always much shorter than propodeal spines. Petiolar node in profile high rounded nodiform and relatively thin, around 1.8 to 2.2 times higher than long (LPeI 45-54), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins usually situated at about same height and moderately rounded, petiolar dorsum distinctly convex; petiolar node in dorsal view around 1.2 to 1.4 times wider than long (DPeI 125-143), in dorsal view pronotum between 2.4 to 2.8 times wider than petiolar node (PeNI 36-42). Postpetiole in profile subglobular and weakly anteroposteriorly compressed, around 1.4 to 1.7 times higher than long (LPpI 60-72); in dorsal view between 1.4 to 1.7 times wider than long (DPpI 143-168), pronotum around 1.6 to 1.7 times wider than postpetiole (PpNI 57-64). Postpetiole in profile appearing more voluminous than petiolar node, postpetiole in dorsal view around 1.5 to 1.7 times wider than petiolar node (PPI 148-167). Mandibles completely unsculptured, smooth, and shiny; clypeus irregularly longitudinally rugose/rugulose with two to seven rugae/rugulae, median ruga rarely fully developed, usually broken, most other rugulae usually broken, sometimes merging with each other; cephalic dorsum between frontal carinae longitudinally rugose, usually with six to seven, rarely eight or nine rugae, rugae running from posterior clypeal margin to posterior head margin, often interrupted, splitting up or with cross-meshes, especially posteriorly; scrobal area partly unsculptured, but mostly merging with surrounding longitudinally rugose to reticulate-rugose sculpture present on lateral head. Ground sculpture on head weakly to moderately punctate. Dorsum and sides of mesosoma reticulate-rugose/rugulose to irregularly longitudinally rugose/rugulose, lateral pronotum sometimes only weakly sculptured and relatively smooth and shining. Forecoxae mostly unsculptured, smooth and shining, sometimes with traces of ground sculpture. Ground sculpture on mesosoma usually weak to absent. Both waist segments and gaster fully unsculptured, smooth, and shining. Dorsum of head with several pairs of long, fine, standing hairs; dorsum of mesosoma with two pairs only, one on anterior pronotum and one on anterior mesonotum; propodeum, waist segments and first gastral tergite without any standing hairs at all; first gastral tergite with very short, scarce, appressed pubescence. Anterior edges of antennal scapes and dorsal (outer) surfaces of hind tibiae usually with appressed, rarely decumbent, hairs. Head, mesosoma, waist segments and gaster usually uniformly chestnut brown to very dark brown, sometimes of lighter reddish brown; appendages usually of slightly lighter brown than remainder of body.

Etymology.

The name of the new species is a combination of the Latin adjective “tenuis”, meaning thin, and the Latin noun “nodus”, meaning node.

Distribution and biology.

Tetramorium tenuinode is widely distributed in eastern Madagascar (Fig. 64). It is found with few interruptions in an almost straight line from Grand Lavasoa and Andohahela in the southeast to Ambanitaza in the northeast. The new species clearly prefers rainforests and montane rainforests at elevations from 25 to 1200 m, even though it was also collected several times from guava forest and urban gardens. In addition, Tetramorium tenuinode appears to be a leaf litter inhabitant since almost all of the material was collected from this microhabitat.

Discussion.

This new species is easily identifiable within its species complex. The presence of well developed, raised, and long frontal carinae separates Tetramorium tenuinode from the species Tetramorium aspis , Tetramorium camelliae , Tetramorium cognatum , Tetramorium karthala , and Tetramorium rumo . These five species are generally also much smaller (WL 0.56-0.81) than Tetramorium tenuinode (WL 0.76-0.94). Also, Tetramorium tenuinode possesses much larger eyes (OI 25-27) than Tetramorium gladius (OI 19-20) and much shorter antennal scapes (SI 66-70) than Tetramorium myrmidon and Tetramorium proximum (SI 74-77). Lastly, the presence of two pairs of long, standing hairs on the dorsal mesosoma distinguishes Tetramorium tenuinode from Tetramorium freya , which lacks any standing hairs on the dorsal mesosoma. The latter species also displays weaker sculpture on the head and mesosoma than Tetramorium tenuinode .

It should be noted, however, that Tetramorium tenuinode is morphologically still very close to Tetramorium proximum , and on very superficial observation it is possible to confuse both. At the initial stage of the revision we considered Tetramorium tenuinode conspecific with Tetramorium proximum , a very variable species. However, after the detailed examination of more than five hundred pinned workers, it became apparent that the material consisted of these two fairly distinct species. Indeed, even though Tetramorium proximum is more broadly distributed than Tetramorium tenuinode , both co-occur in sympatry throughout most of their respective distribution ranges, and both are always very well distinguishable. The most obvious character to separate both species is pilosity on the dorsal mesosoma. In Tetramorium tenuinode this consists of two pairs of long, standing hairs only, one on anterior pronotum and one on anterior mesonotum, which contrasts with the usually five to six (rarely four or more than six) pairs found from anterior pronotum to posterior mesonotum in Tetramorium proximum . In addition to mesosomal pilosity and the shorter antennal scapes mentioned above, Tetramorium tenuinode usually also has a thinner petiolar node in profile, which is around 1.8 to 2.2 times higher than long (LPeI 45-54), while the node of Tetramorium proximum is around 1.7 to 1.9 times higher than long (LPeI 52-60). The identification key presented above might suggest that Tetramorium tenuinode can be easily confused with Tetramorium myrmidon , but this is not the case since the two species differ in a number of characters. Among others, Tetramorium tenuinode has a broader head (CI 91-93), shorter antennal scapes (SI 66-70), and a higher petiolar node (LPeI 45-54) than Tetramorium myrmidon (CI 88-91; SI 74-76; LPeI 58-60).

In contrast to the more variable Tetramorium proximum , Tetramorium tenuinode has little observed intraspecific variation. Some populations vary very slightly in propodeal spine length, thickness of the petiolar node, or body colouration.