Probolomyrmex dentinodis, Oliveira & Feitosa, 2019

Oliveira, Aline M. & Feitosa, Rodrigo M., 2019, Taxonomic revision of the genus Probolomyrmex Mayr, 1901 (Hymenoptera: Formicidae: Proceratiinae) for the Neotropical Region, Zootaxa 4614 (1), pp. 61-94 : 78

Probolomyrmex dentinodis New species

( Figs. 16 , 17 , 18 )

Probolomyrmex petiolatus: Delabie et al. 2001 (misidentification).

Holotype: BRAZIL: Rondônia: Porto Velho, Área Caiçara , 09°26’14.6”S 64°49’58.2”W, 04–18.ix.2012, Vicente R.E. & Oliveira J. cols, C1P2, (worker) [ DZUP, unique specimen identifier DZUP 549762 ].

Paratype: same data as holotype, except: (1 worker) [ MZSP, unique specimen identifier DZUP 549769 ] .

Diagnosis: Petiole higher than long, with the petiolar teeth well developed and forming a conspicuous posterior bifurcation in dorsal view. Subpetiolar process well developed and subrectangular. Prora present. First gastral tergite with a dorsal protuberance on the posterior region.

Worker measurements: (n=8): HL 0.57–0.61; HW 0.35–0.39; SL 0.36–0.44; WL 0.74–0.89; PL 0.23–0.30; PW 0.15–0.19; PH 0.26–0.33; GL 0.94–0.96; TL 2.63–2.74; CI 61.5–64.5; SI 61.5–73.5; PI 106.5–128.5.

Worker description: Frontoclypeal shelflike projection and mandibles with hair-bearing tubercles or cylindrical micro-pegs; external surface of mandibular basal margin transversely micro-striate ( Fig. 16B – esm). Tip of apical segment of antennae bearing minute pits ( Fig. 16C – Ap). Mesopleuron, metapleuron and lateral faces of propodeum alveolate; alveoli denser just above metapleural gland orifice; opening of metapleural gland large, with smooth anterior region, surrounded by rows of hairs ( Fig. 16D ). Petiolar node with incomplete foveae, postero-ventral lobe of petiole and subpetiolar process alveolate, each alveolus with an inner decumbent hair; latero-ventral region of petiole imbricate ( Fig. 16E ). Posterior region of second gastral tergite with transversal rows of deep rounded pits ( Fig. 16A ).

Space between the foveae on the mesosoma covered by dense pubescence. Pygidium with hair-bearing tubercles or cylindrical micro-pegs and some long and thick hairs.

Head 1.6 times longer than wide ( Fig. 17B ). Hypostomal margin curved ( Fig. 16B – he). Antennal scapes extend to head midlength, distance from scape apex of head more than two times pedicel length (SI 61.5–73.5). Propodeum emarginated posteriorly on each side by a low and obtuse carina, with teeth at their apexes. Petiole at least 1.1 times higher than long (PI 106.5–128.5), with postero-dorsal teeth forming a conspicuous bifurcation in dorsal view; posterior face long, concave and smooth; postero-ventral lobe short and rounded; subpetiolar process well developed and subrectangular, with the postero-ventral angle acute and directed towards the gaster ( Fig. 16E ). First gastral segment with prora and a dorsal protuberance on posterior region of tergite, characterized by a gentle elevation of the integument ( Figs. 16A , 17A ).

Queen: (n=2): HL 0.59–0.62; HW 0.39; SL 0.39–0.42. WL 0.80–0.87; PL 0.26–0.28; PH 0.30–0.32 GL 0.96– 1.07; TL 2.61–2.84. CI 62–65; SI 65–67; PI 114–116. Queen presents the characters already described in the genus description and the diagnostic characters of the species ( Fig. 18 ).

Etymology: The name is a reference to the presence of a pair of well developed postero-dorsal teeth on the petiolar node.

Distribution ( Fig. 29 ): Northern Brazil (PA, RO, and TO).

Comments: The subrectangular shape of the subpetiolar process makes this species similar to P. petiolatus . However, P. dentinodis can be easily distinguished from the latter by the presence of a pair of propodeal and petiolar teeth and by the presence of the prora. All the specimens obtained came from leaf-litter samples collected in mature lowland Amazon forests (40m and 200m).

Additional material examined (n=12): BRAZIL: Pará: Alter do Chão, 2°30’S 54°57’W, 1.vii.1998, J.M. Vilhena, D. Agosti det. (1 worker) [ CPDC] ; Marituba, 1°22’S 48°20’W, 19.x.2004, Santos J.R.M., Winkler Cacau (2 workers) [ CPDC] ; (1 worker) [ MPEG]; DZUP 549770 (queen) [ DZUP]; Tocantins: Palmeiras do Tocantins, 06°40’12”S 47°31’48.6”W, 01–09.vi.2005, Silva R.R. & Feitosa R.M. cols (1 queen) [ DZUP] ; (1 worker) [ MZSP]; 06°40’07”S 47°30’56” W, 12–22.vi.2006, Silva R.R. & Feitosa R.M. cols Winkler 12 (1 worker) [ DZUP] ; (1 work- er) [ MZSP] .

Figures

FIGURE 16. SEM micrography of Probolomyrmex dentinodis sp. n. (holotype worker). A. Habitus (pr = prora; ppd = dorsal protuberance in the posterior region of the first gastral tergite). B. Mandibles (he = hypostomal margin; esm = external surface of basal region of mandible). C. Antenna (ap = antennal pit; Lah = long appressed hair; Sh = short hair). D. Metapleural gland. E. Petiole (pil = postero-inferior lobe of petiole; sp = subpetiolar process).

FIGURE 17. Probolomyrmex dentinodis sp. n. (paratype worker). A. Habitus. B. head in frontal view. C. dorsal view.

FIGURE 18. Probolomyrmex dentinodis sp. n. (queen - DZUP 549770). A. Habitus. B. head in frontal view. C. dorsal view.

FIGURE 29. Distribution map for the Neotropical species of Probolomyrmex.