Prionopelta subtilis Overson & Fisher

Overson, Rick & Fisher, Brian L., 2015, Taxonomic revision of the genus Prionopelta (Hymenoptera, Formicidae) in the Malagasy region, ZooKeys 507, pp. 115-150 : 128-131

Taxon classification Plantae Hymenoptera Formicidae

Prionopelta subtilis Overson & Fisher sp. n. Figs 3A, B, 9

Type material.

Holotype, pinned worker, MADAGASCAR, Toamasina, Montagne d’Anjanaharibe, 18.0 km 21° NNE Ambinanitelo, 15.18833°S, 49.615°E, 470 m, rainforest, sifted litter (leaf mold, rotten wood), BLF08002, 8.iii.2003 (B.L. Fisher et al.) (CASC: CASENT0033641). Paratypes, 23 pinned workers with same data as holotype (BMNH: CASENT0033585; CASC: CASENT0033582; CASENT0033586; CASENT0033588; CASENT0033590; CASENT0033591; CASENT0033596; CASENT0033597; CASENT0033598; CASENT0033599; CASENT0033600; CASENT0033601; CASENT0033603; CASENT0033606; CASENT0033610; CASENT0033611; CASENT0033613; CASENT0033614; CASENT0033615; CASENT0033644; MCZC: CASENT0033604; MHNG: CASENT0033584; NHMB: CASENT0033643).

Diagnosis.

Prionopelta subtilis can be recognized by the following combination of characters: twelve antennal segments; minute, densely placed cephalic foveae with raised margins where foveae touch so that the entire head is covered in a delicate mosaic of connected foveae with ridges between; well-defined, uniformly narrow, coronal suture that swells above the level of the surrounding integument; shallow foveae on the pronotum are much larger than those on the head, and more widely spaced, with tiny punctures between.

Worker measurements

(N=20). HL 0.47-0.57 (0.52); HW 0.39-0.45 (0.42); SL 0.26-0.32 (0.29); WL 0.5-0.67 (0.58); PetL 0.14-0.18 (0.16); PetW 0.19-0.26 (0.22); T1W 0.31-0.4 (0.35); CI 76.55-86.41 (80.5); PI 126.32-150.69 (139.98); SI 61.34-71.39 (68.14).

Worker description.

Posterior head margin slightly concave with a noticeable notch medially; cephalic foveae dense and minute; virtually no area of the head lacking foveae in full-face view except at the extreme posterolateral corners; median cephalic band devoid of foveae is thin, linear, and slightly but uniformly swells above the surrounding integument; apical tooth intermediate in length; foveae on the pronotum are shallow, as well as more widely spaced and obviously larger than those on the head, with punctures present between; mesonotum and propodeum consisting of shallow foveae and punctures; metanotal groove visible dorsally, and mesopropodeal suture strongly visible in lateral view.

Etymology.

The name of this species comes from the Latin adjective meaning “fine”, “thin”, or “slender” and refers to the very delicate, net-like patterns produced by the sculpture on the head.

Distribution and ecology.

This common and widespread species is found in rainforest, montane rainforest, lowland rainforest, tropical forest, littoral forest, degraded forest, and marsh edge from 5-1325 meters of elevation (Fig. 13). On the ground it has been collected from inside rotten logs and sticks, as well as under moss, rocks, logs, and in litter. It has also been collected from above-ground sites including canopy moss and leaf litter, as well as inside above-ground twigs and branches.

Taxonomic notes.

Prionopelta subtilis is easy to recognize at a glance under high magnification once several individuals have been observed, as the very small and delicate foveae covering the entire surface of the head produce a unique visual appearance among the Malagasy Prionopelta . The only other confusable species with dense, directly adjacent foveae across the entire head (besides Prionopelta laurae , which would not be mistaken for Prionopelta subtilis ) are Prionopelta seychelles , and some Prionopelta descarpentriesi . Unlike Prionopelta subtilis , Prionopelta seychelles does not possesses a coronal suture medially on the head. Some individuals of Prionopelta descarpentriesi have a dense pattern of touching foveae with a network of ridges between them across the entire head, but these foveae are much larger and deeper than in Prionopelta subtilis . Additionally, this trait in Prionopelta descarpentriesi is accompanied by sculpture on the pronotum that consists almost entirely of large foveae which are similar in size to those on the head, whereas Prionopelta subtilis has much larger foveae on its pronotum than on its head, and these foveae are interspersed with punctures.

Non-type material.

MADAGASCAR: Andasibe, Mantadia NP, 7.i.2006 (A.Ballerio); Antsiranana, 6.5 km SSW Befingotra, Rés. Anjanaharibe-Sud, 14.75°S, 49.5°E, 875 m, rainforest, 19.x.1994 (B.L.Fisher); Antsiranana, 9.2 km WSW Befingotra, Rés. Anjanaharibe-Sud, 14.75°S, 49.4667°E, 1200 m, montane rainforest, 9.xi.1994 (B.L.Fisher); Antsiranana, Betaolana Forest, along Bekona River, 14.53°S, 49.4404°E, 880 m, rainforest, 4.iii.2009 (B.L.Fisher et al.); Antsiranana, Binara Forest, 13.2639°S, 49.5992°E, 1065 m, rainforest, 18.x.2013 (B.L.Fisher et al.); Antsiranana, Forêt de Binara, 9.4 km 235° SW Daraina, 13.2633°S, 49.6°E, 1100 m, montane rainforest, 5.xii.2003 (B.L.Fisher); Antsiranana, Makirovana forest, 14.1651°S, 49.9477°E, 900 m, montane rainforest, 30.iv.2011 (B.L.Fisher et al.); Antsiranana, Makirovana forest, 14.1667°S, 49.95°E, 715 m, rainforest, 2.v.2011 (B.L.Fisher et al.); Antsiranana, Makirovana forest, 14.1604°S, 49.9522°E, 550 m, rainforest, 1.v.2011 (B.L.Fisher et al.); Antsiranana, Makirovana forest, 14.1707°S, 49.9541°E, 415 m, rainforest, 29.iv.2011 (B.L.Fisher et al.); Antsiranana, Parc National de Marojejy, Antranohofa, 26.6 km 31° NNE Andapa, 10.7 km 318° NW Manantenina, 14.4433°S, 49.7433°E, 1325 m, montane rainforest, 18.xi.2003 (B.L.Fisher); Antsiranana, Parc National de Marojejy, Manantenina River, 27.6 km 35° NE Andapa, 9.6 km 327° NNW Manantenina, 14.435°S, 49.76°E, 775 m, rainforest, 15.xi.2003 (B.L.Fisher et al.); Antsiranana, Parc National de Marojejy, Manantenina River, 28.0 km 38° NE Andapa, 8.2 km 333° NNW Manantenina, 14.4367°S, 49.775°E, 450 m, rainforest, 12.xi.2003 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, 12.5178°S, 49.1796°E, 1000 m, montane rainforest, 4.iii.2011 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, 12.5139°S, 49.1778°E, 984 m, montane rainforest, 25.ii.2011 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, 12.5231°S, 49.179°E, 1100 m, montane rainforest, 11.iii.2011 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, 12.5342°S, 49.1761°E, 1325 m, montane rainforest, 12.iii.2011 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, 12.5247°S, 49.1724°E, 1235 m, montane rainforest, 10.iii.2011 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, 3.6 km 235° SW Joffreville, 12.5344°S, 49.1795°E, 925 m, montane rainforest, 20.i.2001 (Fisher, Griswold et al.); Antsiranana, Parc National Montagne d’Ambre, Mahasarika, 12.5318°S, 49.1766°E, 1135 m, montane rainforest, 19.xi.2007 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, Petit lac, 12.5366°S, 49.1741°E, 1130 m, montane rainforest, 17.xi.2007 (B.L.Fisher et al.); Antsiranana, Parc National Montagne d’Ambre, Roussettes, 12.5257°S, 49.1724°E, 1025 m, montane rainforest, 15.xi.2007 (B.L.Fisher et al.); Fianarantsoa, 43 km S Ambalavao, Rés. Andringitra, 22.2333°S, 47°E, 825 m, rainforest, 5.x.1993 (B.L.Fisher); Fianarantsoa, 45 km S. Ambalavao, 22.2167°S, 47.0167°E, 785 m, rainforest, 25.ix.1993 (B.L.Fisher); Fianarantsoa, Forêt d’Ambalagoavy Nord, Ikongo, Ambatombe, 21.8275°S, 47.3389°E, 625 m, 1.xii.2000 (R. Harin’Hala & M.E. Irwin); Fianarantsoa, Forêt de Vevembe, 66.6 km 293° Farafangana, 22.791°S, 47.1818°E, 600 m, rainforest, transition to montane forest, 24.iv.2006 (B.L. Fisher et al.); Fianarantsoa, Réserve Forestière d’Agnalazaha, Mahabo, 42.9 km 215° Farafangana, 23.1938°S, 47.723°E, 20 m, littoral rainforest, 19.iv.2006 (B.L. Fisher et al.); Fianarantsoa, Réserve Spéciale Manombo 24.5 km 228° Farafangana, 23.0158°S, 47.719°E, 30 m, rainforest, 22.iv.2006 (B.L. Fisher et al.); Mahajanga, Réserve Spéciale Marotandrano, Marotandrano 48.3 km S Mandritsara, 16.2832°S, 48.8144°E, 865 m, transition humid forest, 7.xii.2007 (B.L.Fisher et al.); Toamasina, 16 km S Moramanga, 19.0833°S, 48.2333°E, 950 m, rainforest, 18.xi.1990 (P. S. Ward); Toamasina, 5.3 km SSE Ambanizana, Andranobe, 15.6713°S, 49.974°E, 425 m, rainforest, 21.xi.1993 (B.L.Fisher); Toamasina, 6.3 km S Ambanizana, Andranobe, 15.6813°S, 49.958°E, 25 m, rainforest, 14.xi.1993 (B.L.Fisher); Toamasina, 6.9 km NE Ambanizana, Ambohitsitondroina, 15.5851°S, 50.0095°E, 825 m, rainforest, 2.xii.1993 (B.L.Fisher); Toamasina, 6.9 km NE Ambanizana, Ambohitsitondroina, 15.5667°S, 50°E, 1000 m, montane rainforest, 8.xii.1993 (B.L.Fisher); Toamasina, 6 km ESE Andasibe (=Perinet), 18.95°S, 48.4667°E, 900 m, rainforest, 17.xi.1990 (P. S. Ward); Toamasina, Ambanizana, Parc National Masoala, 15.5717°S, 50.0061°E, 925 m, montane rainforest, 26.ii.2003 (D. Andriamalala, D. Silva, et al.); Toamasina, Ambanizana, Parc National Masoala, 15.5722°S, 50.0069°E, 1020 m, montane rainforest, 2.iii.2003 (D. Andriamalala, D. Silva, et al.); Toamasina, Ambatovy, 12.4 km NE Moramanga, 18.8394°S, 48.3084°E, 1080 m, montane rainforest, 8.iii.2007 (B.L.Fisher et al.); Toamasina, Ambatovy, 12.4 km NE Moramanga, 18.8496°S, 48.2947°E, 1010 m, montane rainforest, 3.iii.2007 (B.L.Fisher et al.); Toamasina, Analamay, 18.8062°S, 48.3371°E, 1068 m, montane rainforest, 21.iii.2004 (Malagasy ant team); Toamasina, Ankerana, 18.4067°S, 48.8228°E, 681 m, degraded forest, 28.i.2012 (B.L.Fisher et al.); Toamasina, Ankerana, 18.4064°S, 48.8025°E, 1108 m, montane forest, 19.i.2012 (B.L.Fisher et al.); Toamasina, Ankerana, 18.4104°S, 48.8189°E, 855 m, rainforest, 25.i.2012 (B.L.Fisher et al.); Toamasina, Ankerana, 18.4017°S, 48.806°E, 1035 m, montane forest, 24.i.2012 (B.L.Fisher et al.); Toamasina, Ankerana, 18.4006°S, 48.8131°E, 865 m, rainforest, 17.i.2012 (B.L.Fisher et al.); Toamasina, Ankerana, 18.4083°S, 48.8211°E, 750 m, rainforest, 21.i.2012 (B.L.Fisher et al.); Toamasina, Ankerana, 18.4061°S, 48.8203°E, 725 m, rainforest, 16.i.2012 (B.L.Fisher et al.); Toamasina, Bevolota 17.1 km N Andasibe, 18.7707°S, 48.4316°E, 995 m, montane rainforest, 12.xii.2007 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambatoharanana, 18.8042°S, 48.4008°E, 968 m, rainforest, 12.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambatoharanana, 18.8039°S, 48.4051°E, 1013 m, rainforest, 12.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambatoharanana, 18.804°S, 48.4036°E, 1064 m, rainforest, 12.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambatoharanana, 18.8044°S, 48.4074°E, 960 m, rainforest, 12.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.779°S, 48.3638°E, 918 m, rainforest, 23.xi.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.7791°S, 48.3663°E, 1014 m, rainforest, 23.xi.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.7609°S, 48.3713°E, 1044 m, rainforest, 29.xi.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Ambohibolakely, 18.7613°S, 48.3644°E, 983 m, rainforest, 26.xi.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Tsaravoniana, 18.7612°S, 48.4213°E, 939 m, rainforest, 2.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Tsaravoniana, 18.7637°S, 48.4203°E, 984 m, rainforest, 2.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Tsaravoniana, 18.7646°S, 48.4194°E, 1039 m, rainforest, 4.xii.2012 (B.L.Fisher et al.); Toamasina, Corridor Forestier Analamay-Mantadia, Tsaravoniana, 18.7574°S, 48.423°E, 1018 m, rainforest, 8.xii.2012 (B.L.Fisher et al.); Toamasina, F.C. Andriantantely, 18.695°S, 48.8133°E, 530 m, rainforest, 4.xii.1998 (H.J.Ratsirarson); Toamasina, F.C. Didy, 18.1983°S, 48.5783°E, 960 m, rainforest, 16.xii.1998 (H.J.Ratsirarson); Toamasina, F.C. Sandranantitra, 18.0483°S, 49.0917°E, 450 m, rainforest, 18.i.1999 (H.J.Ratsirarson); Toamasina, Forêt Ambatovy, 14.3 km 57° Moramanga, 18.8508°S, 48.32°E, 1075 m, montane rainforest, 12.iv.2005 (B.L.Fisher); Toamasina, Montagne d’Akirindro 7.6 km 341° NNW Ambinanitelo, 15.2883°S, 49.5483°E, 600 m, rainforest, 17.iii.2003 (Fisher, Griswold et al.); Toamasina, Montagne d’Anjanaharibe, 18.0 km 21° NNE Ambinanitelo, 15.1883°S, 49.615°E, 470 m, rainforest, 8.iii.2003 (Fisher, Griswold et al.); Toamasina, Montagne d’Anjanaharibe, 19.5 km 27° NNE Ambinanitelo, 15.1783°S, 49.635°E, 1100 m, montane rainforest, 12.iii.2003 (Fisher, Griswold et al.); Toamasina, Nosy Mangabe, 7.43 km S Maroantsetra, 15.4973°S, 49.7622°E, 5 m, littoral rainforest edge, 25.vii.2007 (B.L.Fisher et al.); Toamasina, P.N. Mantadia, 18.7917°S, 48.4267°E, 895 m, rainforest, 25.xi.1998 (H.J.Ratsirarson); Toamasina, Parc National de Zahamena, 17.7336°S, 48.7263°E, 950 m, rainforest, 19.ii.2009 (B.L.Fisher et al.); Toamasina, Parc National de Zahamena, Besaky River, 17.7524°S, 48.8532°E, 760 m, rainforest, 22.ii.2009 (B.L.Fisher et al.); Toamasina, Parc National de Zahamena, Onibe River, 17.7591°S, 48.8547°E, 780 m, rainforest, 21.ii.2009 (B.L.Fisher et al.); Toamasina, Parc National de Zahamena, Sahavorondrano River, 17.7526°S, 48.8573°E, 765 m, rainforest, 23.ii.2009 (B.L.Fisher et al.); Toamasina, Parc National de Zahamena, Tetezambatana forest, near junction of Nosivola and Manakambahiny Rivers, 17.743°S, 48.7294°E, 860 m, rainforest, 18.ii.2009 (B.L.Fisher et al.); Toamasina, Reserve Betampona, Camp Rendrirendry 34.1 km 332° Toamasina, 17.924°S, 49.1997°E, 390 m, rainforest, 29.xi.2005 (B.L.Fisher et al.); Toamasina, Reserve Betampona, Camp Vohitsivalana, 37.1 km 338° Toamasina, 17.8867°S, 49.2025°E, 520 m, rainforest, 2.xii.2005 (B.L.Fisher et al.); Toamasina, Réserve Nationale Intégrale Betampona, Betampona 35.1 km NW Toamasina, 17.918°S, 49.2007°E, 500 m, rainforest, 15.xii.2007 (B.L.Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.7702°S, 49.2664°E, 470 m, rainforest, 23.ii.2010 (B.L.Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.7747°S, 49.2655°E, 355 m, rainforest along river, 21.ii.2010 (B.L.Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.7633°S, 49.2669°E, 520 m, rainforest, 22.ii.2010 (B.L.Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.7727°S, 49.2655°E, 450 m, rainforest, 20.ii.2010 (B.L.Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.7691°S, 49.267°E, 475 m, rainforest, 21.ii.2010 (B.L.Fisher et al.); Toamasina, Réserve Spéciale Ambatovaky, Sandrangato river, 16.8175°S, 49.295°E, 360 m, rainforest, 25.ii.2010 (B.L.Fisher et al.); Toamasina, S.F. Tampolo, 10 km NNE Fenoarivo Atn., 17.2825°S, 49.43°E, 10 m, littoral rainforest, 5.iv.1997 (B.L.Fisher); Toamasina, Sahafina forest 11.4 km W Brickaville, 18.8145°S, 48.962°E, 140 m, rainforest, 13.xii.2007 (B.L.Fisher et al.); Toamasina, Torotorofotsy, 18.8708°S, 48.3474°E, 1070 m, montane rainforest, marsh edge, 24.iii.2004 (Malagasy ant team); Toamasina, Torotorofotsy, 18.7705°S, 48.4304°E, 1005 m, montane rainforest, 12.iii.2012 (B.L.Fisher et al.); Toliara, Parc National Andohahela, Col de Tanatana, 33.3 km NW Tolagnaro, 24.7585°S, 46.8537°E, 275 m, rainforest, 28.xi.2006 (B.L.Fisher et al.); Toliara, Parc National d’Andohahela, Manampanihy River, 5.4 km 113° ESE Mahamavo, 36.7 km 343° NNW Tolagnaro, 24.7639°S, 46.7668°E, 650 m, rainforest, 24.i.2002 (Fisher-Griswold Arthropod Team); Toliara, Rés. Andohahela, 6 km SSW Eminiminy, 24.7333°S, 46.8°E, 330 m, rainforest, 4.ii.1993 (P.S.Ward); Toliara, Réserve Spéciale d’Ambohijanahary, Forêt d’Ankazotsihitafototra, 35.2 km 312° NW Ambaravaranala, 18.2667°S, 45.4067°E, 1050 m, montane rainforest, 13.i.2003 (Fisher, Griswold et al.).