Meranoplus sylvarius Boudinot & Fisher

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 : 333-337

Meranoplus sylvarius Boudinot & Fisher sp. n.

( Figs. 10 , 23 , 28 , 29 , 57–62 , 66 )

Holotype worker, MADAGASCAR: Fianarantsoa, Vevembe, 22°47.46’ S, 47°10.91’ E, 600 m, rainforest transition to montane forest, collection code BLF14131, 23–24Apr2006 (B.L. Fisher et al.) (CASC: CASENT017529). Paratype gyne with same data as holotype worker (CASC: CASENT0317567).

Paratype workers with same data as holotype worker (BMNH: CASENT0317527; CASC: CASENT0317536, CASENT0317566, CASENT0070611, CASENT0317528, CASENT0317540–CASENT0317542, CASENT0317557–CASENT0317559, CASENT0317544, CASENT0317547, CASENT0317548, CASENT0317548–CASENT0317552, CASENT0317554–CASENT0317556; MHNG: CASENT0317538; MCZ: CASENT0317543; USNM: CASENT0317549; NHMB: CASENT0317553).

Description

Worker (holotype in parentheses). HL 1.03–1.13 (1.06), HW 0.90–1.02 (0.96), HLA 0.37–0.41 (0.39), CW 0.36–0.38 (0.38), CDD 0.09–0.11 (0.11), SL 0.73–0.80 (0.78), EL 0.22–0.23 (0.23), EW 0.15–0.16 (0.16), PML 0.72–0.80 (0.76), PWA 0.88–0.98 (0.94), PWP 0.47–0.53 (0.48), SPL 0.19–0.22 (0.21), WL 1.04–1.17 (1.12), PTL 0.23–0.25 (0.25), PTH 0.43–0.49 (0.46), PPL 0.23–0.24 (0.24), PPH 0.40–0.45 (0.42), ATW 1.23–1.34 (1.32), ATL 1.27–1.48 (1.42), CI 87.4–90.6 (90.1), SI 77.7–81.3 (81.1), OMI 58.3–59.6 (59.4), CDI 23.9–-31.2 (27.3), SEI 324–355 (336), PMI 122.7–124.4 (122.8), PWI 51.5–55.3 (51.5), CS 1.0–1.1 (1.0), EYE 37.7–40.4 (38.5) (7 measured).

Chocolate brown to almost black.

Head longer than broad (CI 77–82). Mandibles with nearly parallel striation. Face with dilute costae which veer away from posterior margin of head; area anterior to nuchal carina without rugae or areolation. Area around eyes costate; costae in malar area somewhat rugose. Frontal carinae comparatively narrow, not concealing margin of eyes in full-face view. Scrobal carina weakly developed; anterior half bulging. Anterior margin of clypeus with weakly bilobed lamina; lobes close-set (CDI 24–31). Middle portion of clypeus shining and weakly costate; lateral thirds of middle portion with about two costae; middle third without costae. Eyes large (EYE 35–41). Maximum length of eye distinctly less than ¾ length of malar area (OMI 55–60). Face with erect to subdecumbent setae of various lengths. Setae ventrally and anterior to the eye mostly subdecumbent.

Promesonotal shield longer than broad (PMI 122–125); posterolateral corners close-set (PWI 51–55). Dorsum of promesonotum with dilute costae, mostly concentrated in anterior half; interstices with setae raised on tiny nodules. Promesonotal shield setae decumbent to suberect, of mixed lengths. Lateral face of pronotum with weak rugae; setae raised on nodules. Lateral face of mesonotum smooth and shining. Katepi-anepisternal suture present; mesopleural-mesonotal suture present; mesopleural-metapleural suture absent to present. Mesopleuron smooth and strongly shining, with very dilute (1 to 4), very weak indications of raised sculpture other than in posteroventral area. Metapleural lobes well-developed. Propodeal spines thornlike; dorsomedian carina absent; dorsolateral carina extends dorsolaterally to promesonotum. Posterior face of propodeum smooth and shining; very weak costae may be present in top third, which otherwise has setae raised on nodules.

Petiole cuneate in profile, without pedicel. Anteroventral process of petiole a simple denticle. Postpetiole nodiform, about as tall as long (PTI 50–55). Sub-post-petiolar process well-developed, with a strong inflection between posterior half of sternum. Dorsal face of postpetiole with weak to indistinct rugae; lateral face with weak to indistinct rugae; posterior face smooth and shining except for nodulose setae and transverse costae near extreme base. Fourth abdominal tergum (ATIV) comparatively small (ATW/WL 1.15–1.23, ATL/HL 1.20–1.33). ATIV shining, with fine areolate sculpture between stellate setiferous punctures; smooth near base of tergum. Setae of ATIV of mixed lengths; shortest subdecumbent and longer than width of metafemora; longest setae about twice as long as shortest.

Queen (paratype). HL 1.22, HW 1.17, HLA 0.41, CW 0.44, CDD 0.13, SL 0.82, EL 0.29, EW 0.22, SPL 0.20, WL 1.61, PTL 0.31, PTH 0.56, PPL 0.29, PPH 0.56, ATW 1.82, ATL 1.89, CI 95.2, SI 70.6, OMI 71.4, CDI 29.1, SEI 285, CS 1.2, EYE 42.4.

Color: chocolate brown.

Large (WL 1.61). Head longer than broad (CI 95). Mandibles with more-or-less parallel striae. Face with weakly rugose costae which continue to the posterior margin of the head. Area above eye areolate; behind and beneath eye costate. Scrobal carina weakly bulging in anterior half. Anterior margin of clypeus with two welldeveloped, close-set laminar lobes (CDI 29). Middle portion of clypeus with strong costae in lateral thirds; middle third without sculpture. Eyes large (EYE 42). Maximum eye length about ¾ length of malar area (OMI 71). Scapes long (SI 71). Face with erect to subdecumbent setae; longest setae about 1.5 length of shortest setae.

Mesosoma longer than tall. Anterolateral corners of pronotum angled; dorsolateral margin of pronotum ecarinate. Mesosomal dorsum with little sculpture: pronotum smooth medially, rugose laterally; scutum smooth and shining in anterior half, with dilute rugae in posterior half; scutellum with transverse rugae branching more frequently in lateral portions. Mesosomal dorsum with subdecumbent to erect setae of mixed lengths. Lateral face of pronotum rugose anteriorly; with setae raised on strong nodules. Katepisternum mostly smooth and shining; without costae extending longitudinally margin to margin. Anteroventral portion of anepisternum smooth and shining; dorsal portion with longitudinal rugae, interstices roughened. Metapleuron roughened with rugae; area anteroventral to propodeal spiracle smooth and shining. Propodeal spines thorn-like, long (SPL 0.20). Meso and metatibial spurs absent. Wings unknown.

Petiole cuneate in profile; subpetiolar process dentiform. Postpetiole nodiform; sternal process large. Dorsal and lateral faces of postpetiole rugose; posterior face roughened near base and with dilute longitudinal costae. Forth abdominal tergum (ATIV) with sides convex; nearly as broad as long (ATW/GL 0.96). ATIV with fine, weak areolate sculpture between stellate setiferous punctures; weak, dilute costae present in basal region. ATIV with subdecumbent short setae; suberect setae about 1.5-2 times as long as shorter setae.

Diagnosis

Worker. The absence of meso- and metatibial spurs is unique in the Malagasy fauna. This new species may be separated from M. radamae by the absence of a dorsomedial costa extending from the base of the propodeal spine to the promesonotum.

Gyne. The combination of stellate setiferous punctures, comparatively large size (WL 1.61), dark chocolatebrown color, malar area about ¾ the length of the eye (OMI 71.4), long scapes (SI 70.6), uniquely identify gynes of this species in the Malagasy fauna.

Comments

The type series of M. sylvarius is designated from a large nest collection from the rainforest/montane forest of Vevembe, the only known locale of this species. Restriction to moist forest habitat is unique for Malagasy Meranoplus .

Although not collected in sympatry with M. radamae , M. sylvarius is morphologically distinct enough to support the hypothesis of reproductive isolation. The lack of meso- and metatibial spurs is unique in the Malagasy Meranoplus fauna. Although M. radamae shows much geographic variation in its sculpturation, the trends of sculpture reduction across body parts never move in synchrony to such extremes, suggesting that the almost complete reduction of sculpture on specimens of M. sylvarius would be highly unlikely under circumstances of gene flow.

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 23 – 24. Mesosomata of Meranoplus workers in oblique posterolateral view. 23. Meranoplus radamae: propodeal spine with dorsomedian costa reaching notopropodeal suture (CASENT 0486686; A. Nobile 2007). 24. Meranoplus sylvarius: propodeal spine without dorsomedian costa reaching notopropodeal suture (CASENT 0317529).

FIGURES 27 – 28. Propodea of Meranoplus gynes in lateral view. 27. Meranoplus cryptomys: short, triangular propodeal spines (CASENT 0132374). 28. Meranoplus sylvarius: long, thornlike propodeal spines (CASENT 0317567; E. Ortega 2012).

FIGURES 29 – 30. Illustrations of Meranoplus gyne heads in oblique posterolateral view. 29. Meranoplus sylvarius: single subocular carina indicated in red (CASENT 0132374). 30. Meranoplus radamae: two subocular rugae indicated in red (CASENT 0317524).

FIGURES 57 – 59. M. sylvarius sp. n., holotype worker (CASENT 0317539). 57. Body in lateral view. 58. Body in dorsal view. 59. Head in full-face view.

FIGURES 60 – 62. M. sylvarius sp. n., paratype gyne (CASENT 0317567; S. Hartman 2012). 60. Body in lateral view. 61. Body in dorsal view. 62. Head in full-face view.

FIGURES 63 – 66. Distribution maps of Malagasy Meranoplus species; type localities are indicated by red markers. Elevation is indicated by color: green 0 – 100 m, peach 101 – 500 m, pink 501 – 1000 m, grey 1001 – 2000 + m (map provided by NASA). 63. M. cryptomys sp. n. 64. M. mayri. 65. M. radamae; the exact type locality is unknown, but is in “ Central Madagascar ”. 66. M. sylvarius sp. n.