Platythyrea sagei

This is the first species known to have an ergatoid male in the genus Platythyrea. Observations have suggested that these males contribute to colony labor (Boudinot et al., 2016).

Identification
Boudinot et al. (2016): Indomalayan species with posterodorsally bilobate petiolar node, node longer than wide in dorsal view, eye larger than 0.30 mm, and worker pedicel longer than EL and antennomere 3 length. The ergatoid male is unique among Platythyrea species.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Singapore. Oriental Region: India.

Biology
Boudinot et al (2015): Ergatoid males of Platythyrea sagei were encountered by AAW outside of the nest in association with workers. Workers and males were observed coming out of the nest and returning. Some males were observed to carry debris (possibly vegetative); workers of the same colony carried live minors of Dorylus orientalis Westwood, 1835. Males were distinguishable in the field from workers by their average smaller size (average total length worker = 7.68, male = 7.31), more slender build, less agile movement, and obvious lack of a sting. In the vast majority of species male ants do not contribute to colony welfare; indeed there are no well-known exceptions. The observations recorded here suggest a limited contribution of labor by males.

Nomenclature

 * . Platythyrea sagei Forel, 1900d: 315 (w.) INDIA (Himachal Pradesh, Karnataka).
 * Type-material: lectotype worker (by designation of Boudinot, Wachkoo & Bharti, 2016: 60).
 * [Note: Boudinot, Wachkoo & Bharti, 2016: 60, inadvertently use the queen symbol for the lectotype; Forel mentions only workers in both key and description. Other original syntype workers are from Dharmsala (Fulton), and Belgaum (Wroughton).]
 * Type-locality: lectotype India: Dharmsala, IV/5 (Sage).
 * [Note: Boudinot, Wachkoo & Bharti, 2016: 60, overlooked the fact that Brown, 1976: 52, had selected Belgaum as the type-locality.]
 * Type-depository: MHNG (lectotype); other original syntypes in MCZC, MHNG.
 * Boudinot, Wachkoo & Bharti, 2016: 60 (ergatoid m.).
 * Status as species: Bingham, 1903: 74; Forel, 1906b: 91; Emery, 1911d: 29; Viehmeyer, 1916a: 112; Menozzi, 1939a: 327; Chapman & Capco, 1951: 49; Brown, 1975: 9, 52; Bolton, 1995b: 336; Tiwari, 1999: 32; Bharti, Guénard, et al. 2016: 53; Boudinot, Wachkoo & Bharti, 2016: 60 (redescription).
 * Distribution: India.

Description
Unless otherwise noted the text for the remainder of this section is reported from Boudinot et al (2016)

Worker

Characters not in original description: Head (Fig. 1). Frontal lobes convex, separated by a shallow, median sulcus that ends posteriorly where the lobes pass into the short, round-edged, parallel frontal carinae, visibly demarcated from clypeus. Anterior clypeal margin strongly produced, subtriangular. Posterior clypeal margin fine but reasonably distinct. Apical tooth of masticatory mandibular margin largest; other nine teeth alternating, larger and smaller. Scapes long, robust, thickest beyond midlength. Compound eyes glabrous. Body after head (Figs. 3, 5). Mesosomal dorsum unevenly convex in profile; pronotum with dorsal and lateral faces meeting at a round angle; metanotum slightly constricted in middle; metanotal groove lacking; propodeal spiracle small, slit shaped. Dorsal and ventral margins of propodeal tubercles discontinuous with propodeum in profile view. Petiole subquadrate in profile, anterodorsal margin sloping anteriorly, node highest posteriorly, sides subvertical; node broadly rectangular in dorsal view, longer than wide; lateral margins feebly convex, anterior margin convex; notch between lobes of posterodorsal margin shallow, lobes narrowly separated. Cinctus between pre- and postsclerites of abdominal segment III very weak, without cross-ribbbing. Coarse punctures present on body.

Measurements (n = 9, average in parentheses): EL 0.38 - 0.40 (0.39); GL 2.58 - 2.84 (2.67); HL 1.66 - 1.71 (1.68); HW 1.32 - 1.37 (1.35); PL 0.75 - 0.78 (0.77); PnW 0.87 - 0.94 (0.90); PW 0.54 - 0.57 (0.55); SL 1.49 - 1.54 (1.51); WL 2.49 - 2.60 (2.55). Indices: CI 78.4-82.5 (80.4) (> 91 in BROWN 1975); EI 27.9 - 30.3 (28.9); PI 70.1 - 75.0 (72.4); SI 109.5 - 116.7 (112.4); SI2 58.0 - 60.2 (59.4).

Ergatoid Male

Highly similar to worker; head (Fig. 2), body after head (Figs. 4, 6).

Exceptional characters for male of the genus (general state in brackets): Ergatoid (alate); antenna geniculate (antenna not geniculate); scape elongate, slightly shorter than head length (scape short, SL < EL); frontal lobes partially concealing antennal socket in full-face view (antennal sockets fully exposed); eyes only slightly larger than those of worker (eyes much larger); head capsule of similar volume as worker (volume smaller); ocelli very small, pinprick-like (ocelli well-developed); malar space elongate, slightly shorter than EL (malar space very narrow); palps reduced (palps long); legs, including coxae, robust (legs slender, weak); mesosoma of similar volume as that of worker and permanently apterous, sclerites not developed for flight (mesosoma with alate condition); pronotum, propodeum, and petiole of similar dimensions as those of worker (pronotum, propodeum, petiole smaller); helcium diameter equivalent to that of worker (helcium broader).

Differences from worker: Head size and proportions smaller relative to body size (differences between average metrics for each caste: wHL - mHL = 0.23, wHW - mHW = 0.22, wCI - mCI = 2.27, wWL - mWL = 0.07); antennae 13-merous; pedicel length about 0.33× that of antennomere 3; compound eyes proportionally larger (EI 35.4 - 36.0 vs. 27.9 - 30.3); ocelli present; supraclypeal area larger; distance across frons between antennal toruli narrower; masticatory margin of mandibles with 8 - 9 denticles (vs. 10); dorsal mandibular face matte (vs. shining), sculpture smaller and rougher; propodeal denticles smaller; ventral head surface (postgenal bridge), propleurae, procoxae, femora, and metasomal sterna with fewer stubble-like setae.

Genitalic description: Pygostyles present. Abdominal sternum IX (Fig. 12) large, triangular; length about 2× width; spiculum short; anterolateral sternal margins tapering posterolaterally. Cupula (not figured) anteroposteriorly short; foramen genitale narrowed; dorsal face narrower than lateral faces. Basimere length about 2.33× maximum width in dorsal view (Fig. 7) and about 1.3× maximum height in profile view (Fig. 9); basimere dorsomedian margins parallel anteriorly for about 0.14× length before diverging until past midlength before becoming parallel again for about 0.3× length (Fig. 7); ventromedian margins parallel for about 0.3× basimeral length before diverging (Fig. 8). Telomeres (Figs. 7 - 10) glabrous; wedge-shaped in profile view, apices narrowly rounded apically; telomere maximum length about 2× maximum height in profile view (Fig. 9). Basivolsella (Figs. 8, 10, 13, 14) ventrolateral margin sinuate, ventroapical angle or process acutely triangular, weakly developed; basivolsellar setae coarse, short; cuspis (Figs. 8, 13) lobate, anteroposterior length about 1.5× dorsoventral height; digitus (Figs. 8, 10, 13, 14) apex clavate and twisted such that ventroapical margins almost perpendicular with digital shaft and ectal face directed posteriorly; digitus anteroposterior length about equal to dorsoventral height. Penisvalvae dorsally fused (Fig. 7); valvura (not figured) long, directed posterodorsally; valviceps (Fig. 11) dorsal margin with two concavities and three convexities; apex produced, subtruncate; ventral margin strongly sinuate, with two concavities and convexities; ventral margin serrate along anterior two thirds; lateral apodeme linear, almost reaching apex. Note that genitalic proportions described above are approximate.

Measurements (n = 3): EL: 0.40 - 0.41 (0.40); GL: 2.52 - 2.70 (2.63); HL: 1.44 - 1.46 (1.45); HW: 1.11 - 1.15 (1.13); PL: 0.72 - 0.80 (0.76); PnW 0.89 - 0.91 (0.90); PW: 0.50 - 0.52 (0.51); SL: 1.39 - 1.41 (1.40); WL: 2.45 - 2.50 (2.48). Indices: CI: 77.1 - 78.8 (78.1); EI 35.4 - 36.0 (35.7); PI: 65.0 - 69.4 (67.2); SI: 123.0 - 126.1 (123.9); SI2 56.4 - 56.7 (56.5).

Measurements and Indicies: EL - Eye length, maximum diameter of eye with head oblique to show full eye surface. GL - Gaster length, maximum length of the gaster in lateral view from the anteriormost point of the first gastral segment (third abdominal) to the posteriormost point. HL - Head length, length of head capsule from anterior clypeal margin to mid-point of posterior head margin in full-face view. HW - Head width, maximum width of head, excluding eyes, in full-face view. PL - Petiole length, maximum length of petiole from anterior process to posterior most point of tergite, where it articulates with helcium. PnW - Pronotum width, maximum width of pronotum in dorsal view. PW - Petiole width, maximum width of petiole in dorsal view. SL - Scape length, maximum length of scape, excluding the basal neck and condyle. WL - Weber's length, diagonal length of mesosoma, measured in lateral view from the anterior pronotal margin, excluding the collar, to posterior extremity of propodeal lobe. CI - Cephalic index, HW / HL × 100. EI - Eye index, EL / HW × 100. PI - Petiole index, PW / PL × 100. SI - Scape index, SL / HW × 100. SI2 - Scape index 2, SL / WL × 100.

References based on Global Ant Biodiversity Informatics

 * Boudinot B. E., A. A. Wachkoo, and H. Bharti. 2016. The first ergatoid male of Platythyrea (Hymenoptera: Formicidae: Ponerinae), with contribution to colony labor suggested by observation and comparative morphology. Myrmecological News 22: 59-64.
 * Brown W. L., Jr. 1975. Contributions toward a reclassification of the Formicidae. V. Ponerinae, tribes Platythyreini, Cerapachyini, Cylindromyrmecini, Acanthostichini, and Aenictogitini. Search Agric. (Ithaca N. Y.) 5(1): 1-115.
 * Dubey A.K. 2006. Notes on the Indian species of the genus Platythyrea (Hymenoptera: Formicidae), with an identification key. Entomon 31: 45-48.
 * Emery C. 1911. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125.
 * Forel A. 1900. Les Formicides de l'Empire des Indes et de Ceylan. Part VII. J. Bombay Nat. Hist. Soc. 13: 303-332.
 * Forel A. 1906. Les fourmis de l'Himalaya. Bulletin de la Société Vaudoise des Sciences Naturelles 42: 79-94.
 * Musthak Ali T. M. 1991. Ant Fauna of Karnataka-1. Newsletter of IUSSI Indian Chapter 5(1-2): 1-8.
 * Narendra A., H. Gibb, and T. M. Ali. 2011. Structure of ant assemblages in Western Ghats, India: role of habitat, disturbance and introduced species. Insect Conservation and diversity 4(2): 132-141.
 * Ramachandra T. V., M. D. Subash Chandran, N. V. Joshi, A. Narendra, and T. M. Ali. 2012. Ant species composition and diversity in the Sharavathi Rivers basin, central Western Ghats. Sahyadri Conservation Series 3, ENVIS Technical Report 20. 51 pages.
 * Tiwari R. N. 1999. Taxonomic studies on ants of southern India (Insecta: Hymenoptera: Formicidae). Memoirs of the Zoological Survey of India 18(4): 1-96.