Recurvidris nigrans, Zettel, 2008

Zettel, H., 2008, On the ants (Hymenoptera: Formicidae) of the Philippine Islands: III. The genus Recurvidris BOLTON 1992, Linzer biologische Beiträge 40 (1), pp. 891-895 : 892-893

Recurvidris nigrans nov.sp.

E t y m o l o g y: The Latin adjective "nigrans" means dark and refers to the dark body colour of the new species that differs from all other hitherto known congeners.

T y p e m a t e r i a l: Holotype worker labelled " Philippines: Negros Or., Cuer-\ nos de Negros, Valencia\ Apolong, Casaroro Falls, 28.\ 1.2007, leg. H. Zettel (456)", in the Entomological Collection of the University of San Carlos, Cebu City, Philippines. 10 paratype workers labelled " Philippines: Negros Oriental\ Cuernos d.N., Valencia\ Apolong, Casaroro Falls\ 3- 4.3.2008, lg. Zettel (513)" in the Natural History Museum Vienna, Austria, and in the author's collection.

T y p e l o c a l i t y Philippines, Negros Island, Negros Oriental Province, Cuernos de Negros Mountains (= Mount Talinis ), municipality of Valencia , barangay Apolong , Casaroro Falls ; 9° 16' N, 123° 12' E, c. 500-550 m a.s.l. ( GPS) .

D i a g n o s i s (worker):Body chiefly blackish brown, funiculusof antenna and tarsi yellowish. Body surface smooth and shiny. Head broad, HW 0.61-0.65, CI 99-103. Cly- peus without distinct carinae. Mandible with four acute teeth on apical margin and one prominent, acute tooth at basal margin ( Fig. 4 ). Propodeum dorsally with 1-2 pairs of short decumbent setae, with long, slender, recurved spines ( Fig. 1 ), without infradental lamellae between spines and metapleural lobes. Petiole ( Fig. 1 ) with very slender peduncle ventrally bearing a spiniform subpetiolar process; node in lateral view forming an acute angle anteriorly (at insertion of anterior setae).

D e s c r i p t i o n (worker):

Measurements of holotype: TL 3.2; HL 0.63; HW 0.65; CI 103; SL 0.57; SI 89; PW 0.35; AL 0.86. Measurements of paratypes (n = 10): TL 2.9-3.2; HL 0.61-0.64; HW 0.61-0.65; CI 99-102; SL 0.56-0.59; SI 89-94; PW 0.34-0.35; AL 0.81-0.86.

Head ( Figs 2, 3 ) broad and smooth, lacking sculpture except hair pits, setiferous pits and some rugae near mandible base. Mandible ( Fig. 4 ) smooth and shiny, with some relatively large hair pits, apical margin with four teeth, forth tooth acute, basal margin with one acute tooth almost as large as forth tooth of apical margin. Clypeus ( Fig. 4 ) without paired carinae, but with indistinct paired elongate swellings. Eyes ( Fig. 1 ) comparatively large, containing 8 ommatidia in longest row. Profile shape of alitrunk, petiole and postpetiole as in Figure 1 . Alitrunk smooth and polished, with some very fine setiferous pits, only part of mesopleuron with some fine rugae. Promesonotum with 4 pairs of setae plus one median seta posteriorly. Impression behind mesonotum appearing angular in profile. Propodeum comparatively high, dorsal surface with 1-2 pairs of short subcumbent setae in front of spiracle; spines very high, slender, divergent, and in caudal view very narrow (blade-like). Petiole ( Fig. 1 ) with 2-3 pairs of dorsal setae; peduncle in profile long and very slender, its dorsal outline distinctly concave and ending posteriorly in a sharp angle at insertions of anterior pair of setae (insertions separated from each other by shallow impression), its ventral outline with long, spiniform subpetiolar process; node low. Postpetiole with 3 dorsal pairs and 1 ventrolateral pair of setae, low and with deep helcium, as typical for the genus. Gaster moderately depressed. Petiole, postpetiole, and gaster polished except for very fine setiferous pits. Colour blackish brown, alitrunk, petiole and postpetiole slightly lighter. Scape of antenna brown, funiculus yellowish. Mandibles brown, distally yellowish. Legs dark brown, but tarsi yellowish.

C o m p a r a t i v e n o t e s: Recurvidris nigrans nov.sp. meets all morphological criteria of the R. kemneri group listed by BOLTON (1992), i.e., the characteristic dentition of the mandible ( Fig. 4 ), the absence of infradental lamellae on the propodeal declivity, and a broad head ( Fig. 2 ) (range of CI 94-106 in the group, 99-103 in R. nigrans nov.sp.). This species group contains only two further taxa, R. kemneri (WHEELER & WHEELER 1954) from Borneo and Java and R. proles BOLTON 1992 from Sulawesi. Comparing the key characteristics which distinguish these two species, R. nigrans sp. nov. is more similar to R. proles , because it is relatively large in size, lacks clypeal carinae and bears 1-2 pairs of setae on the propodeal dorsum. The dark body colour of R. nigrans nov.sp. differs from both species (as well as from all other congeners!); R. kemneri is uniformly yellow, R. proles is yellow with brown head and gaster. Further differences between R. nigrans nov.sp. and R. proles are the following: The tooth on the basal margin of the mandible is strongly developed in R. nigrans nov.sp. (almost as large as the forth tooth, Fig. 4 ), but small in R. proles . The dorsum of the propodeum bears short, decumbent setae in R. nigrans nov.sp., but comparatively long standing setae in R. proles . The subpetiolar process is narrow, relatively long and acute in R. nigrans nov.sp. ( Fig. 1 ), but small and triangular in R. proles (for the latter two characteristics see BOLTON 1992: fig. 8). " Recurvidris sp_phi1" from Camarines Sur in southern Luzon ( ALPERT & al. 2008: see figures) differs from the new species by much smaller size (TL c. 2.1, HW c. 0.4), uniformly yellow colour, and a relatively stout petiolar peduncle in lateral aspect. On average, R. nigrans nov.sp. is the largest known species of Recurvidris.

Figures

Figs 1-4: Recurvidris nigrans nov.sp., paratype worker (HW 0.63 mm, AL 0.82 mm) in the Natural History Museum Vienna. (1) Habitus, lateral view; (2) Habitus, dorsal view; (3) Head, full face view; (4) Head in oblique view showing dentition of mandibles.