Terataner balrog

Terataner balrog is known from Tsingy de Bemaraha and Kirindy in arid, western Madagascar where it was sampled from tropical dry forest habitats. It seems to live in twigs and branches on low vegetation above ground, as well as in tree stumps on the ground and in roots in the ground. Foragers can be found in the lower vegetation and in smaller numbers also on the ground. (Hita Garcia et al. 2017)

Identification
Hita Garcia et al. (2017) - Terataner balrog can be diagnosed by the following combination of characters: in full-face view head subrectangular and barely longer than wide (CI 93-97); petiole and postpetiole without long, dorsal spines; postpetiole in profile relatively thin and anteroposteriorly compressed, with high and acute triangular dorsum; postpetiole in dorsal view extremely wide, shield-like with sharp transverse crest, apex of dorsum bilobate; dorsum of pronotum conspicuously transversely sulcate/porcate; petiole and postpetiole conspicuously sculptured.

The new species is a highly distinguishable member of the Malagasy fauna and cannot be confused with any congener. Of special importance are the strongly transverse porcate sculpture on the pronotal dorsum and the shape of petiole and postpetiole. The sculpture on the pronotal dorsum appears to be unique at present since we did not observe it in another congeneric species. Not considering the sculpture, one can also easily separate T. balrog from all other Terataner on the basis of the postpetiolar shape.

Worker Caste Ergatoid queen caste
 * usually larger body size ((HW 1.13-1.33; WL 1.46-1.84)
 * longer antennal scapes (SI 77-89)
 * slightly larger eyes (OI 24-29)
 * promesonotal dorsum anteriorly broader (PMI 145-163)
 * slightly thinner metafemorae (HFI 304-338)
 * in dorsal view petiolar node less broad (DPeI 113-140)
 * dorsal petiolar teeth thinner
 * in anterodorsal view postpetiole more triangular and less massive
 * postpetiole in dorsal view less broad (DPpI 205-234)
 * gaster not greatly enlarged
 * pronotal dorsum always transversely sculptured and mesonotal dorsum longitudinally sculptured
 * lateropronotum with six to seven thick, diagonally arranged, parallel sulci
 * less hairy
 * head and mesosoma of darker colour
 * doi:10.1371/journal.pone.0172641.t003
 * usually smaller body size (HW 1.00-1.10; WL 1.40-1.56)
 * slightly shorter antennal scapes (SI 72-76)
 * slightly smaller eyes (OI 21-24)
 * promesonotal dorsum anteriorly thinner (PMI130-134)
 * slightly thicker metafemorae (HFI 321-357)
 * in dorsal view petiolar node broader (DPeI 129-158)
 * dorsal petiolar teeth thicker
 * in anterodorsal view postpetiole arc-like and much more massively shaped
 * postpetiole in dorsal view much broader (DPpI 249-340)
 * gaster greatly enlarged
 * promesonotal dorsum variably sculptured, usually highly irregularly sculptured
 * lateropronotum usually with four very thick, diagonally arranged, parallel sulci
 * much hairier
 * head and mesosoma of lighter colour

Intraspecific variation. The worker caste of T. balrog is remarkably uniform with no significant, observable intraspecific variation. There is some variation in body size (WL 1.46-1.84), which is well within the normal range of many myrmicine ants. The ergatoid queens display more variation, as can be seen from the above description. Especially the shape of the postpetiolar dorsum and the sculpture on the dorsal promesonotum are unique in every single specimen studied and vary to a great extent between them.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Ergatoid Queen
No alate or dealate queens occur in any of the Malagasy Terataner species. Colonies are almost always monogynous with a single reproductive, an ergatoid queen, that differs only slightly from corresponding workers. This reproductive lacks both wings and ocelli, and has an almost normal, worker-like thorax. The ergatoid queen is externally distinguishable from workers only by very subtle characters (e.g., small spines or tubercles below the mesonotal groove; a unique pattern of rugae on the sides of the pronotum) that vary among species. Ergatoid queens have ovaries bearing two to three ovarioles.

Nomenclature

 *  balrog. Terataner balrog Hita Garcia in Hita Garcia et al., 2017: 12, figs. 1, 3B, 3D, 4-7 (w.) MADAGASCAR.

Worker
(N = 15). HL 1.18-1.43 (1.28); HW 1.11-1.33 (1.20); FLD 0.50-0.60 (0.55); SL 0.94-1.03 (0.99); EL 0.28-0.33 (0.30); OMD 0.38-0.50 (0.45); WL 1.46-1.84 (1.64); PH 0.52-0.64 (0.59); PW 0.96-1.16 (1.06); PML 0.62-0.76 (0.69); PDH 0.54-0.64 (0.59); MFL 0.94-1.24 (1.10); MFW 0.30-0.38 (0.35); PTH 0.51-0.68 (0.60); PTL 0.30-0.40 (0.35); PTW 0.39-0.53 (0.45); PPH 0.56-0.71 (0.63); PPL 0.28-0.36 (0.32); PPW 0.64-0.85 (0.72); CI 93-97 (94); FLI 45-48 (46); OI 24-29 (25); OMI 64-74 (68); SI 77-89 (82); DMI 63- 67 (64); LMI 34-38 (36); PMI 145-163 (154); PPDI 96-104 (100); MFLI 84-99 (91); HFI 304- 338 (316); LPeI 54-66 (59); DPeI 113-140 (126); LPpI 44-56 (51); DPpI 205-234 (224).

HEAD. Masticatory margin of mandible with five or six teeth, usually with large, acute apical tooth followed by a smaller, acute subapical tooth, remaining three to four teeth conspicuously smaller and less acute, very often worn down to small, rounded remnants. Palp formula 5,3. Head in full-face view subrectangular and weakly longer than broad (CI 93-97), sides of head convex and weakly broader behind eye level; posterior head margin weakly rounded; anterior clypeal margin medially with distinct, broad but shallow impression; frontal carinae very well developed, from level of posterior frontal lobes to shortly before posterior head margin subparallel and moderately raised, posteriorly sharply divergent leading to posterolateral corners and stronger raised, crest-like, separating side of head from posterodorsal head; posterior corners with very sharp, strongly raised carinae shortly before occipital margin, dorsalmost point of carinae shaped into short, conspicuous, acute teeth/ horns, teeth/horns visible in full-face view. Antennal scrobes strongly reduced to almost absent; antennal scapes moderately long, not reaching posterior head margin (SI 77-89). Eyes of moderate size (OI 24-29), malar area around 1.4 to 1.6 times longer than maximum eye length (OMI 64-74).

MESOSOMA. In lateral view mesosomal outline moderately low (LMI 34-38) with conspicuously convex promesonotum separated from convex propodeum by noticeable but shallow metanotal groove, pronotum approximately of same height as propodeum (PPDI 96-104); promesonotal suture present laterally and completely absent dorsally (pronotum and mesonotum dorsally clearly separated by different surface sculpture-see below); metanotal groove conspicuously developed, shallowly and broadly impressed, in profile anterodorsal propodeal margin weakly overhanging metanotal groove. Pronotum strongly marginate from lateral to dorsal mesosoma; anterodorsally denticulate with pair of large, triangular, and blunt horns laterally; mesonotum only weakly marginate and armed with pair of short, thick and blunt acute teeth laterally; in dorsal view promesonotum anteriorly around 1.4 to 1.6 times wider than long (PMI 145-163). Propodeum strongly marginate from sides to dorsum and sides to propodeal declivity, propodeum unarmed, posterodorsal corners angulate; propodeal lobes well developed, broadly triangular, and blunt. All femorae well swollen medially; length of metafemur around 3.0 to 3.4 times longer than maximum width (HFI 304-338).

WAIST SEGMENTS & GASTER. Petiolar node conspicuously triangular cuneiform and relatively high, with two short, thick, and blunt dorsal teeth; in profile petiolar node approximately 1.5 to 1.9 times higher than long (LPeI 54-66); in dorsal view node approximately ua1.1 to 1.4 times wider than long (DPeI 113-140). Postpetiole in profile relatively thin and anterodorsally compressed, with high and acute triangular dorsum, around 1.8 to 2.3 times higher than long (LPpI 44-56), in anterodorsal view extremely wide, shield-like with sharp transverse crest, apex of dorsum bilobate, postpetiole in dorsal view between 2.0 to 2.3 times wider than long (DPpI 205-234). Gaster not extremely enlarged.

SCULPTURE. Mandibles unsculptured and smooth to weakly rugose/rugulose; cephalic dorsum almost completely longitudinally rugose with more or less regularly arranged rugae, rugae slightly weaker laterally in frontal scrobe area adjacent to frontal carinae; malar area reticulate-rugose; microsculpture on head mostly weakly punctate, especially pronounced between frontal carinae and in scrobal area, absent on clypeus and mandibles. Mesosoma very conspicuously rugose to porcate; dorsum of pronotum conspicuously transversely sulcate/porcate; lateropronotum with very thick, diagonally arranged, parallel sulcate carinae (usually six to seven); dorsal mesonotum longitudinally, partly radiating, sulcate/porcate; lateral mesonotum and propodeum longitudinally rugose; dorsum of propodeum and propodeal declivity unsculptured, smooth and shiny; microsculpture on mesosoma weakly to moderately reticulate-punctate; legs unsculptured, smooth, and shining. Peduncle unsculptured, smooth and shiny; petiolar node anteriorly only weakly sculptured with faint rugae; node laterally and dorsally conspicuously sulcate/porcate, sulci usually arranged longitudinally, sometimes irregularly so; anterior face of postpetiole transversely sulcate, posterior face with longitudinally to irregularly sulcate; microsculpture on both waist segments weakly to moderately reticulate-punctate. Whole gaster with very noticeable and dense reticulate-punctate to punctate microsculpture, base of first gastral tergite longitudinally rugose/rugulose.

PILOSITY & PUBESCENCE. Whole body covered with abundant, short to moderately long, fine, suberect to erect pilosity; pilosity on head noticeably shorter; mandibles with appressed to decumbent hairs; antennal scapes with abundant, shorter, decumbent to suberect hairs on all sides, and often also with row of widely spaced, much longer, erect hairs on anterior margin. Pubescence strongly reduced to absent.

COLORATION. Head, mesosoma, waist segments, and gaster very dark brown to black, antennae and mandibles dark brown, legs yellowish orange to very light brown.

Queen
Ergatoid. (N = 5). HL 1.11-1.14 (1.12); HW 1.00-1.10 (1.04); FLD 0.51 (0.51); SL 0.75-0.82 (0.78); EL 0.22-0.26 (0.24); OMD 0.36-0.40 (0.38); WL 1.40-1.56 (1.49); PH 0.54-0.62 (0.59); PW 0.91-0.96 (0.94); PML 0.68-0.73 (0.71); PDH 0.57-0.62 (0.60); MFL 0.89-0.94 (0.94); MFW 0.25-0.28 (0.27); PTH 0.60-0.64 (0.62); PTL 0.31-0.35 (0.33); PTW 0.45-0.53 (0.50); PPH 0.61-0.70 (0.65); PPL 0.25-0.33 (0.30); PPW 0.81-0.85 (0.82); CI 90-96 (93); FLI 46-51 (49); OI 21-24 (22); OMI 59-69 (63); SI 72-76 (74); DMI 61-65 (63); LMI 39-40 (39); PMI 130-134 (132); PPDI 94-103 (97); MFLI 86-89 (87); MFI 321-357 (341); LPeI 50-56 (53); DPeI 129-158 (144); LPpI 36-52 (46); DPpI 249-340 (282).

Ergatoid. HEAD. Masticatory margin of mandible with five teeth, usually with large, acute apical tooth followed by a smaller, acute subapical tooth, remaining three teeth conspicuously smaller and less acute, very often worn down to small, rounded remnants. Palp formula 5,3. Head in full-face view subrectangular and weakly longer than broad (CI 90-96), sides of head convex and weakly broader behind eye level; posterior head margin weakly rounded; anterior clypeal margin medially with distinct, broad but shallow impression; frontal carinae very well developed, from level of posterior frontal lobes to shortly before posterior head margin subparallel and moderately raised, posteriorly sharply divergent leading to posterolateral corners and stronger raised, crest-like, separating side of head from posterodorsal head; posterior corners with very sharp, strongly raised carinae shortly before occipital margin, dorsalmost point of carinae shaped into short, conspicuous, acute teeth/horns, teeth/horns visible in full-face view. Antennal scrobes strongly reduced to almost absent; antennal scapes short to moderately long, not reaching posterior head margin (SI 72-76). Eyes of moderate size (OI 21-24), malar distance around 1.4 to 1.7 times longer than maximum eye length (OMI 59-69).

MESOSOMA. In lateral view mesosomal outline moderately low (LMI 39-40) with conspicuously convex promesonotum separated from convex propodeum by noticeable but shallow metanotal groove, pronotum approximately of same height as propodeum (PPDI 94-103); promesonotal suture present laterally and completely absent dorsally (pronotum and mesonotum dorsally partly separated by different surface sculpture); metanotal groove conspicuously developed, shallowly and broadly impressed, in profile anterodorsal propodeal margin weakly overhanging metanotal groove. Pronotum strongly marginate from lateral to dorsal mesosoma; anterodorsally denticulate with pair of moderately large, triangular, and blunt horns laterally; mesonotum only weakly marginate and armed with pair of short, thick and blunt acute teeth laterally; in dorsal view promesonotum anteriorly around 1.3 times wider than long (PMI 130-134). Propodeum strongly marginate from sides to dorsum and sides to propodeal declivity, propodeum unarmed, posterodorsal corners angulate; propodeal lobes well developed, broadly triangular, and blunt. All femorae well swollen medially; length of metafemur around 3.2 to 3.6 times longer than maximum width (HFI 321-357).

WAIST SEGMENTS & GASTER. Petiolar node conspicuously triangular cuneiform and relatively high, with two short, thick, and blunt dorsal teeth; in profile petiolar node around 1.8 to 2.0 times higher than long (LPeI 50-56); in dorsal view node around 1.3 to 1.6 times wider than long (DPeI 129-158). Postpetiole in profile relatively thin and anterodorsally compressed, with high and acute triangular dorsum, around 1.9 to 2.8 times higher than long (LPpI 36-52), in anterodorsal view extremely wide, shield-like with sharp transverse crest, apex of crest variably shaped, ranging from roughly bilobate or thickly serrated to smooth and rounded, postpetiole in dorsal view between 2.5 to 3.4 times wider than long (DPpI 249-340). Gaster extremely enlarged.

SCULPTURE. Mandibles unsculptured and smooth; cephalic dorsum almost completely conspicuously longitudinally rugose with more or less regularly arranged rugae, rugae slightly weaker laterally in frontal scrobe area adjacent to frontal carinae; malar area reticulate-rugose; microsculpture on head conspicuously punctate, especially pronounced between frontal carinae and in scrobal area, absent on clypeus and mandibles. Mesosoma very conspicuously rugose to porcate; dorsum of pronotum and mesonotum variably sculptured, ranging from mostly transversely sulcate/porcate pronotal dorsum with irregular elements merging to mostly longitudinally sulcate/porcate with irregular elements to completely irregularly sulcate/porcate on both; lateropronotum with very thick, diagonally arranged, parallel sulcate carinae (usually four); lateral mesonotum and propodeum longitudinally rugose; dorsum of propodeum weakly rugose; propodeal declivity unsculptured, smooth and shiny; microsculpture on mesosoma weakly to moderately reticulate-punctate; legs unsculptured, smooth, and shining. Peduncle unsculptured, smooth and shiny; petiolar node anteriorly only weakly sculptured with faint rugae; node laterally and dorsally conspicuously sulcate/porcate, sulci usually arranged longitudinally, sometimes irregularly so; anterior face of postpetiole transversely sulcate, posterior face with longitudinally to irregularly sulcate; microsculpture on both waist segments weakly to moderately reticulate-punctate. Whole gaster with very noticeable and dense reticulate-punctate to punctate microsculpture, basal third of first gastral tergite longitudinally rugose/rugulose.

PILOSITY & PUBESCENCE. Whole body covered with abundant, moderately long, fine, suberect to erect pilosity; pilosity on head shorter; mandibles with subdecumbent to suberect hairs; antennal scapes with abundant, shorter, decumbent to suberect hairs on all sides, and often also with row of widely spaced, much longer, erect hairs on anterior margin. Pubescence strongly reduced to absent.

COLORATION. Similar to worker caste but head and mesosoma with patches of much lighter brown, especially dorsolateral margins of pronotum.

Intercaste variation. Among the material of the new species available to us, we identified four ergatoid queens that are morphologically close to the worker caste. Nevertheless, despite this superficial similarity, the ergatoids are separable from the workers. Within the examined colonies the ergatoid queens turned out to be the smallest adult females that were conspicuously much hairier and of lighter colour than the workers. In addition, among other characters, the ergatoid reproductives possess shorter antennal scapes, smaller eyes, smaller anterolateral horns/teeth on the pronotal dorsum, a less broad promesonotum, thicker hind femorae, a broader petiolar node, thicker dorsal petiolar teeth, a broader postpetiole, a significantly much larger gaster, and different sculpture (for a detailed list of intercaste differences see Table 3). It remains unclear if the differences observed in T. balrog are typical for the whole genus. On the basis of a first examination of ergatoids from more than a dozen species, it appears as if some worker-ergatoid differences will be observable in all or most species, such as the smaller body size and eyes, shorter antennal scapes, thicker dorsal petiolar teeth/spines (if present in the species), wider and generally more massive postpetiole, as well as lighter body colour and irregularly arranged surface sculpture. Nevertheless, general trends and patterns of ergatoid queen versus worker morphologies will be assessed in detail in a future revision of the whole genus.

Type Material
Holotype, pinned worker, Madagascar, Mahajanga, Parc National Tsingy de Bemaraha, 2.5 km 62Ê ENE Bekopaka, Ankidrodroa River, -19.13222°, 44.81467°, 100 m, tropical dry forest on tsingy, sifted litter (leaf mould, rotten wood), collection code BLF04340, 11.XI.2001 (B.L. Fisher et al.) (: CASENT0472559).

Paratypes, 25 pinned workers and one ergatoid queen: two pinned workers with same data as holotype (CASC: CASENT0472560; CASENT0472561); six workers and one ergatoid queen with same data as holotype but collected from rotten tree stump and collection code BLF04373 (CASC: CASENT0426613; CASENT0426614; CASENT0426617; : CASENT0426612); and 17 workers from Mahajanga, Parc National Tsingy de Bemaraha, 3.4 km 93Ê E Bekopaka, Tombeau Vazimba, -19.14194°, 44.828°, 50 m, tropical dry forest, collected ex rotten log and dead twig, and as ground foragers, collection codes BLF04238, BLF04283, and BLF04296, 6.XI.2001 (B.L. Fisher et al.) (: CASENT0426920; CASC: CASENT0426921; CASENT0426922; CASENT0426923; CASENT0426983; CASENT0426984; CASENT0426985; CASENT0426986; CASENT0426987; CASENT0426988; CASENT0427001; CASENT0746134; CASENT0746136; {{HLMD}: CASENT0426926; MCZC: CASENT0426924).

Cybertypes, volumetric raw data, 3D PDFs, and 3D rotation videos of the physical holotype (CASC: CASENT0472559) and the paratype ergatoid queen (CASC: CASENT0426614) in addition to montage photos illustrating head in full-face view, profile and dorsal views of the body of both specimens. The data is deposited in Dryad (http://dx.doi.org/10.5061/dryad.sk6s0) and can be freely accessed as virtual representations of the types.

Etymology
The new species is named after the fictional evil creature from J. R. R. Tolkien’s “Lord of the Rings” trilogy in reference to the “dark” predatory lifestyle common within the genus Terataner, as well as its strongly armoured and horned gestalt. The species epithet is a noun in apposition and thus invariant.

References based on Global Ant Biodiversity Informatics

 * Hita Garcia F., G. Fischer, C. Liu, T. L. Audisio, G. D. Alpert, B. L. Fisher, and E. P. Economo. 2017. X-Ray microtomography for ant taxonomy: An exploration and case study with two new Terataner (Hymenoptera, Formicidae, Myrmicinae) species from Madagascar. PLoS ONE 12(3): e0172641.