Meranoplus radamae Forel, 1891

Boudinot, Brendon E. & Fisher, Brian L., 2013, A taxonomic revision of the Meranoplus F. Smith of Madagascar (Hymenoptera: Formicidae: Myrmicinae) with keys to species and diagnosis of the males, Zootaxa 3635 (4), pp. 301-339 : 327-331

Meranoplus radamae Forel, 1891

( Figs. 9 , 14 , 16–18 , 20, 22, 24, 30, 32, 48–56, 65)

Meranoplus radamae Forel, 1891: 148 , pl. 4, fig. 10. Lectotype worker, here designated, MADAGASCAR: Imerina (Central Madagascar) (M. Hildebrandt) (MHNG: CASENT0101239) [examined].

Description

Worker. HL 0.86–1.04, HW 0.79–0.92, HLA 0.32–0.38, CW 0.29–0.36, CDD 0.08–0.10, SL 0.60–0.72, EL 0.18–0.22, EW 0.13–0.16, PML 0.58–0.76, PWA 0.73–0.92, PWP 0.43–0.55, SPL 0.16–0.22, WL 0.86– 1.1.05, PTL 0.18–0.25, PTH 0.38–0.46, PPL 0.19–0.26, PPH 0.32–0.42, ATW 1.01–1.24, ATL 1.09–1.40, CI 88.7–93.8, SI 70.5–79.4, OMI 55.9–62.7, CDI 22.4–34.2, SEI 290–350, PMI 121.3–134.3, PWI 54.0–62.5, CS 0.8–1.0, EYE 36.2–40.5 (19 measured).

Coloration variable: dark orange, orange brown or yellowish brown with yellow abdominal segments IV–VII. Head longer than broad (CI 92–95). Mandibles striate. Face longitudinally rugose to dilutely costate; area anterior to nuchal carina areolate to rugose. Area around eyes areolate to rugose or costate beneath and behind. Frontal carinae concealing dorsal margin of eyes in full face view. Scrobal carina weak to nearly absent. Anterior margin of clypeus with weakly bilobed lamina; lobes relatively close set (CDI 22–36). Middle portion of clypeus costate to rugose laterally; smooth and shining medially. Setae on face subdecumbent to erect; of mixed lengths; longest setae about twice as long as shortest.

Promesonotal shield longer than broad (PMI 120–134). Lateral margins of promesonotum tapering to midline posteriorly; posterolateral denticles comparatively close-set (PWI 54–63). Dorsum of promesonotum areolate to dilutely rugose. Setae on promesonotal shield subdecumbent to erect; of mixed lengths; longest setae about 1.25 as long as shortest. Lateral face of pronotum rugose anteriorly; posterior portion shining, variably smooth to weakly areolate; setiferous nodules mostly hidden by sculpture. Lateral face of mesonotum smooth and shining to somewhat roughened. Anapleural and mesometapleural sutures present. Mesopleuron shining; with or without weak areolate sculpture or costae on katepisternum. Metapleuron shining with or without weak areolation; smooth anterodorsal metapleural bulla. Lateral face of propodeum shining, roughened with rugae dorsal to spiracle. Propodeal spines long, thorn-shaped (0.16–0.22), with both dorsolateral and dorsomedian costae reaching notopropodeal suture. Posterior face of propodeum with costae in dorsal region.

Petiole cuneate in profile although sometimes with bulge posteriorly near apex; without pedicel. Subpetiolar process dentiform. Anterior and posterior faces of petiole smooth and shining. Postpetiole nodiform; without distinct posterodorsal angle. Dorsal face of postpetiole areolate to rugose; lateral face rugose; posterior face areolate to rugose. Fourth abdominal tergite (ATIV) can be small (ATW/WL 1.13–1.33, ATL/WL 1.15–1.48). ATIV base variably rugose and rough to shining between setiferous punctures. ATIV with fine areolate sculpture, which may be weak, between stellate setiferous punctures. ATIV setae of mixed lengths; short setae subdecumbent; long setae suberect; longest setae 1.25–1.5 times as long as shortest setae.

Queen. HL 1.09–1.15, HW 1.05–1.10, HLA 0.35–0.38, CW 0.37–0.41, CDD 0.10–0.13, SL 0.70–0.74, EL 0.26–0.29, EW 0.21, SPL 0.19–0.23, WL 1.39–1.49, PTL 0.27–0.31, PTH 0.47–0.49, PPL 0.24–0.30, PPH 0.47–0.52, ATW 1.47–1.58, ATL 1.68–1.92, CI 92.1–96.1, SI 68.0–70.3, OMI 72.6–78.5, CDI 25.9–32.8, SEI 253–283, CS 1.1, EYE 43.3–44.8 (6 measured).

Light brown to pale yellowish orange.

Small (WL 1.4–1.5). Head longer than broad (CI 92–97). Mandibles striate; ridges may be evenly curved or wavy. Face areolate to longitudinally rugose; area posterior to ocelli areolate to transversely rugose. Area above and below eyes areolate; areolate to rugose behind eyes. Scrobal carina distinct to indistinct; broadest in anterior half. Anterior margin of clypeus with bilobed lamina; lobes relatively close-set (CDI 26–33). Middle portion of clypeus rugose to costate laterally, smooth medially; lateral ridges may meet anteriorly. Eyes large (EYE 43–53). Maximum eye length ¾ length of malar area (OMI 73–79). Scapes long (SI 67–70). Face with setae of mixed lengths; longest setae 1.25–2 times as long as shortest setae.

Pronotum with anterolateral angles; dorsolaterally ecarinate. Pronotal dorsum variably areolate to rugose. Scutum smooth to rugose on anterior half; always with some rugae on posterior half. Scutellum areolate to longitudinally rugose. Lateral face of pronotum areolate to sub-areolate on anterior portion; shining, roughened, sometimes with rugae on posterior portion. Katepisternum smooth and shining, with longitudinal costae often extending from anapleural suture to mesometapleural suture. Anepisternum shining ventrally; rugose dorsally. Metapleuron and lateral face of propodeum rugose, with variable shining area anterodorsal to metapleural bulla. Propodeal spines long, thorn-like (SPL 0.19–0.23). Wings as in Meranoplus male diagnosis.

Petiole cuneate in profile, without pedicel. Postpetiole nodiform, without distinct posterodorsal angle. Subpostpetiolar process well-developed; robust to thin. Dorsal face of postpetiole areolate to rugose; lateral face rugose-costate; posterior face areolate with interstices punctate to longitudinally rugose. Fourth abdominal tergum (ATIV) with sides convex in dorsal view; long (ATL/WL 1.20–1.29). Base of ATIV rough to smooth, with variably developed rugae; setiferous punctures strong near base, increasing in stellation posteriorly; ATIV with weak fine areolation between setiferous punctures. ATIV setae of mixed lengths: short setae subdecumbent, shortest setae about ½ length of longest setae; long setae erect, varying in density.

Male. HL 0.52–0.63, HW 0.55–0.60, HLA 0.06–0.09, SL 0.15–0.18, EL 0.24–0.26, EW 0.19–0.23, WL 0.70–1.20, PTL 0.19–0.25, PTH 0.20–0.22, PPL 0.15–0.19, PPH 0.19–0.22, ATW 0.79–1.01, ATL 0.83–0.96, CI 96.3–106.4, SI 27.0–29.7, OMI 301–428, SEI 61–69, CS 0.5–0.6, EYE 75.9–80.5 (3 measured).

Body piceous brown, appendages light brown.

Small (WL 0.7–1.2, CS 0.5–0.6). Head longer than broad or broader than long (CI 96–106). Mandibles variably developed: short and spatulate with edentate masticatory margin to longer, bladelike, with apical tooth. Frontal carinae distinct to indistinct. In full-face view, posterior margin of head not raised above ocelli greater than distance between lateral ocelli. Head variably rugose with foveate sculpture. Scapes short (SI 27–30). Eyes large (EYE 76–81), greater than three times as long as malar area (OMI 300–430). Ocelli about the size of the antennal socket. Majority of setae on body shorter than eye length, subdecumbent to erect, uniformly straight to evenly curved.

Notauli distinct; may continue to posterior margin of scutum after converging. Parapsidal lines distinct, impressed or not. Scutum smooth and shining, albeit undulating with coarse setiferous punctures. Scutellum shining at least medially; roughened laterally. Katepisternum smooth and shining. Anepisternum smooth and shining; posterior half variably rough and rugose to smooth and shining. Lower half of metapleuron with a shining patch of variable size; dorsal half rugose. Posterior face of propodeum with longitudinal costae laterally; variably foveate to smooth.

Petiole and postpetiole shape variable (PTI 87–114, PPI 72–95). Petiole and postpetiole sessile; apex of petiolar node node acute to rounded; postpetiole subglobose. Petiolar sternum occasionally with setae. Postpetiolar sternum setose. Fourth abdominal tergum shining, with weak, fine areolate sculpture and with stellate setiferous punctures. Fourth abdominal sternum shining.

Foramen genitale constricted; basal ring broadening posteriorly; basimere longer than tall; basimere dorsomedian margin folded ventrally; basimere ventromedian margin dorsally curved, cupping the volsella; telomere arrowhead-shaped with a ventral membrane basally; setae of cuspis numerous, subequal in length to the apex of the telomere in ventral view; basal setose region of cuspis triangular; ventral margin of cuspis edentate, evenly curved; digitus long, thin, narrowing to apex which is evenly ventrally curved; valviceps of penisvalva strongly rounded with an apicoventral lobe; valvura apex subrectangular, narrow; ventral margin of penisvalva slightly concave to straight in basal half, otherwise straight and serrate, with teeth short and pointed anteriorly.

Diagnosis

Worker. Workers of this species are immediately differentiable from M. mayri by the absence of promesonotal spines. The following characters diagnose this species within the M. nanus group: posterolateral denticles close-set (PWI <64); meso- and metatibial spurs present; dorsomedian costa of propodeal spine present, extending to promesonotum; postpetiole posterior face never smooth and shining.

Gyne. Within the Malagasy Meranoplus fauna, gynes of M. radamae may be identified by the following characters: stellate setiferous punctures present on fourth abdominal tergum; propodeal spines thorn-like; smooth area behind eyes interrupted by rugae, or ruga behind eye terminates at ventrolateral mandibular condyle; eye length about ¾ length of malar area (OMI mean 75); never bicolored nor dark brown.

Male. Males of M. radamae may be separated from those of M. mayri by the presence of the following characters: posterior margin of head not visible in full face view; small (WL 0.70–1.20); eyes large (EYE 76–81); maximum eye length greater than or equal to three times length of malar area (OMI 301–428); head comparatively small (CS 0.5–0.6); apex of penisvalva evenly rounded; penisvalva with apicoventral lobe; ventral margin of penisvalva serrate, without long spine-like teeth.

Comments

Meranoplus radamae is restricted to the grasslands and woodlands of the High Plateau, and the spiny forests of southern Madagascar. Specimens are known from 370–1550 m above sea level, and nests have been collected under stones in grassland and from ground nests. A few collections have been made in southern rainforest sites, but these may represent local adaptation to disturbed habitats. It is interesting to note that the southern rainforest collections of M. radamae , at R.S. Kalambatitra and Mount Vasiha, have reduced sculpturation on the face and promesonotal shield; these characters are represented in extreme form by the distinct M. sylvarius described here.

Material examined

MADAGASCAR: Antananarivo, Ambatolaona, 18°55.68’ S, 47.52.97° E, 1382 m, urban/garden, coll’n codes BLF16883, BLF16899, 19Feb2007 (B.L. Fisher et al.); Antananarivo, Angavokely, 18°56’ S, 47°45’ E, 10Feb1992 (B. Pettersson); 29.5 km WNW Tolanaro, Vasiha Mt., 24°55’37” S, 46°44’49” E, 300 m, sifted leaf litter in rainforest, 6–7Feb1995 (K.C. Emberton et al.); Antananarivo, Ankalalahana, 19.00659° S, 47.11220° E, 1375 m, Uapaca woodland, coll’n codes BLF26350, BLF26357, BLF26360, BLF26366, BLF2637, BLF26391, 29–31Mar2010 (B.L. Fisher et al.); Antananarivo, Antsahadinta, 19°00.76’ S, 47°27.40’ E, 1403 m, urban garden, coll’n codes BLF17519, BLF17522, 8May2007 (B.L. Fisher et al.); Antananarivo, Arivonimamo, Navoatra, 18.97799° S, 47.11929° E, 1373 m, Uapaca woodland, coll’n code ARA915, 6–8May2010 (A. Ravelomanana); Antananarivo, Manalalondo, Antaponimanadala, 19.25531° S, 47.17710° E, 1984 m, savanna grassland, coll’n code ARA1053, 13–16May2010 (A. Ravelomanana); Fianarantsoa, Ambositra, Antapia, 20.71971° S, 47.08685° E, 1495 m, Uapaca woodland, coll’n code ARA600, 3–5Feb2010 (A. Ravelomanana); Fianarantsoa, Ambositra, Mampiarika, 20.73456° S, 47.08355° E, 1480 m, Uapaca woodland, coll’n code ARA468, Feb2010 (A. Ravelomanana); Fianarantsoa, Ambositra, Mampiarika, 20.73568° S, 47.08384° E, 1464 m, Uapaca woodland, coll’n code ARA469, 1–3Feb2010 (A. Ravelomanana); Fianarantsoa, Forêt Atsirakambiaty 7.6 km 285° WNW Itremo, 20°35.6’ S, 46°33.8’ E, 1550 m, under stone in grassland, coll’n codes BLF7206, BLF7226, 22–26Jan2003 (B.L. Fisher et al.); Fianarantsoa, Itremo, Ampangabe, 20.6119° S, 46.60688° E, 1414 m, savanna woodland, coll’n code ARA791, 21–23Mar2010 (A. Ravelomanana); Fianarantsoa, Itremo, Antohatsahomby, 20.55436° S, 46.58438° E, 1640 m, Uapaca woodland, coll’n code ARA611, 18Mar2010 (A. Ravelomanana); Mahajanga, Ambohimanga, 18°45.67’ S, 47.33.86’ E, 1361 m, disturbed montane rainforest, coll’n code BLF17326, 26Apr2007 (B.L. Fisher et al.); Toliara, R.S. Kalambatitra, 23.4185° S, 46.4583° E, 1365 m, grassland, coll’n codes BLF21500, BLF21538, BLF21535, 8Feb2009 (B.L. Fisher et al.); Toliara, Forêt Vohidava 88.9 km N Amboasary, 24°14’26” S, 46°17’16” E, 500 m, coll’n codes BLF15846, BLF15847, BLF15849, BLF15850, BLF15692, BLF15738, 9Dec2006 (B.L. Fisher et al.); Toliara, Vohibasia Forest, 59 km E Sakaraha, 22°28’ S, 44°51’ E, 750 m, sifted litter in tropical dry forest, coll’n code BLF1310, 13Jan1996 (B.L. Fisher et al.).

Figures

FIGURES 8 – 11. Labrum of Meranoplus species, ectal view. 8. Meranoplus mayri worker (CASENT 0317545). 9. Meranoplus radamae worker (CASENT 0317561). 10. Meranoplus sylvarius worker (CASENT 0317566). 11. Meranoplus mayri male (CASENT 0317565).

FIGURES 13 – 14. Right volsella and paramere of Meranoplus species, in mesal view displaying the digitus, cuspis, basimere, and telomere. 13. Meranoplus mayri (CASENT 0317564). 14. Meranoplus radamae (CASENT 0115117).

FIGURES 15 – 16. Right penisvalva of Meranoplus species, ectal view. 15. Meranoplus mayri (CASENT 0317564). 16. Meranoplus radamae (CASENT 0115117).

FIGURES 17 – 18. Right fore- and hindwings of a M. radamae gyne, dorsal view (CASENT 0317562). Fused veins are indicated by a plus sign, “ + ”, and crossveins by a dash, “ - ”. Cell names are indicated in italics. 17. Forewing. 18. Hindwing.