Prionopelta minuta, Ladino & Feitosa, 2020

Ladino, Natalia & Feitosa, Rodrigo M., 2020, Taxonomic revision of the genus Prionopelta Mayr, 1866 (Formicidae: Amblyoponinae) for the Neotropical region, Zootaxa 4821 (2), pp. 201-249 : 234-236

Prionopelta minuta sp. n.

Figures 23–24 , 35C

Holotype worker. BRAZIL: Rondônia: Itapuã do Oeste, Floresta Nacional do Jamari , -9.9780 -62.9780, 03- 10.iii.2016, A.C. Ferreira & L. Cunha cols., Winkler, DZUP549780 (1 specimen) [ DZUP].

Paratype workers. s ame data as holotype, DZUP549781 (1 specimen) [ DZUP] ; DZUP549782 (1 specimen) [ DZUP]; DZUP549783 (1 specimen) [ DZUP]; DZUP549784 (1 specimen) [ DZUP]; DZUP549785 (1 specimen) [ DZUP]; DZUP5490786 [ DZUP]; DZUP549787 (1 specimen) [ DZUP]; DZUP549788 (1 specimen) [ DZUP]; DZUP549789 (1 specimen) [ DZUP]; DZUP549790 (3 specimens) [ MCZ]; DZUP549791 (2 specimens) [ USNM]; DZUP549792 (3 specimens) [ MZSP]; DZUP549793 (2 specimens) [ INPA]; DZUP549794 (2 specimens) [ ICN]; DZUP549795 (1 specimen) [ MPEG] .

Diagnosis. Lateral portion of frons with foveolate sculpturing nearly confluent and inconspicuous shiny interspaces appearing as small raised margins. Twelve antennomeres. Posterior margin of subpetiolar process straight.

Holotype measurements. HL 0.43; HW 0.37; SL 0.23; WL 0.51; PrL 0.22; PrW 0.25; PetNL 0.13; PetW 0.20; PetH 0.14; PetL 0.14; T1L 0.20; T1W 0.30; TL 1.28; CI 86; SI 62; PetI 153; PetHI 100; PetWI 142.

Worker measurements (n=7). HL 0.42–0.48; HW 0.36–0.40; SL 0.22–0.24; WL 0.48–0.51; PrL 0.20–0.23; PrW 0.24–0.27; PetNL 0.11–0.14; PetW 0.16–0.21; PetH 0.12–0.16; PetL 0.12–0.14; T1L 0.18–0.22; T1W 0.28– 0.31; TL 1.24–1.32; CI 81–90; SI 55–63; PetI 114–175; PetHI 85–133; PetWI 114–175.

Queen measurements (n=1). HL 0.53; HW 0.48; SL 0.27; WL 0.73; PrL 0.15; PrW 0.31; PetNL 0.13; PetW 0.28; PetH 0.19; PetL 0.19; T1L 0.25; T1W 0.46; TL 1.70; CI 90; SI 55–63; PetI 215; PetHI 100; PetWI 147.

Worker description. Body light yellow. Integument covered by deep and dense foveolate sculpturing with inconspicuous shiny spaces between the fovea on the lateral portion of frons, appearing as small raised margins in full-face view. Pubescence abundant over the entire body. Head longer than broad; length of median tooth of mandible shorter than basal tooth; basal margins of mandibles slightly convex. Clypeus evenly rounded to slightly projecting medially. Twelve antennomeres; antennomeres 1–4 separated by deep constrictions. Eyes placed immediately posterior to the head midlength. Pronotum broader than long. Distance between the propodeal spiracles and the bulla of the metapleural gland corresponding to one spiracular diameter; distance between the propodeal spiracles and the propodeal dorsum corresponding to almost two spiracular diameters. Petiolar node as long as high. Subpetiolar process subtriangular, with anterior and posterior margins converging apically; posterior margin straight; posteroventral angle obtuse.

Queen. Distance between the propodeal spiracles and the bulla of the metapleural gland corresponding to half spiracular diameter; distance between the propodeal spiracles and the propodeal dorsum equal to two spiracular diameters. Posteroventral angle of the subpetiolar process obtuse.

Male. Unknown.

Etymology. The name refers to the comparative small size of this species. From Latin, minuta = small.

Distribution ( Fig. 35C ). Prionopelta minuta is known from southwestern Colombia and northern Brazil.

Comments. This species can be confused with P. modesta since both have a dense foveolate sculpturing on the head dorsum and twelve antennomeres. Comparatively, P. modesta comprises larger ants, with interspaces between fovea of the lateral portion of frons moderately spaced and posterior margin of the subpetiolar process clearly concave. Prionopelta minuta groups smaller ants, with nearly confluent foveolate sculpturing and posterior margin of the subpetiolar process straighter. The last feature mentioned for P. minuta is useful to separate the species from other Neotropical members of the genus, as well as the body length of workers, always lesser than 1.40 mm.

Most of the specimens known so far for P. minuta come from the Amazon rainforests of the Brazilian states of Rondônia and Amazonas. The transitional areas between these forests and the Brazilian savanna (Cerrado) are extremely fire-sensitive, and anthropogenic activities related with deforestation for crop and livestock establishment as well as global warming have shown negative effects on their biodiversity (Pivello 2009; Shlisky et al. 2009; Silveira et al. 2013).

Intriguingly, the species has been recorded in the lowlands of the central and meridional Brazilian Amazon and in the western slopes of the Andean mountain range, Colombia. Although we cannot presently discard the possibility that this species is widely distributed in the western Amazon realm, further collection records are required to confirm the disjunct distribution of P. minuta .

Natural history. The species is mainly known from leaf litter and dead wood samples collected in well preserved forests; reported at elevations of 152-1430m.

Additional material examined (126 specimens). BRAZIL: Amazonas: 59°48’W 2°25’S, 20.ix.1996, A.C. Maicedo e outros #1682, ZF3- Km 41 (2 workers) [ INPA]. Lg. Marianill, 24 Km NE of Manaus, ix.1962, W.L. Brown col., #4566 (4 workers) [ MZSP]. Manaus , 13.xii.1993, A.B. Casimiro col. (1 worker) [ CEPEC]; same data, 16.iv.1988, H. Vasconcelos, #4642 (5 workers) [ CEPEC]; same data, 29.ix.1993, A.B. Casimiro col. (4 workers) [ CEPEC]; same data, 10.xi.1993, A.B. Casimiro col., Rs 1202 (10 workers) [ INPA]; same data, 14.xii.1993, A.B. Casimiro col., 4832, Rs 1301 (6 workers) [ INPA]; same data, 23.i.1994, A.B. Casimiro col., #4832, Rs 3114 (4 workers) [ DZUP]; same data, 2°5’86”S 60°6’55°W, 20.x.2004, Baccaro e col., Winkler, TEAM-ZF-2- Km 14, B1- PO-0139, 1m 2 de liteira (1 worker) [ INPA]; B1 -PO-0153 (1 worker) [ INPA]; same data, 21.x.2004, B1-PO-0126 (1 worker) [ INPA]; B1 - PO-0137 (1 worker) [ INPA]; B1 - PO-0159 (1 worker) [ INPA]; B1 - PO-0160 (1 worker) [ INPA]; B1 - PO-0157 (1 worker) [ DZUP]. Fazenda Experimental da UFAM, 2°39’17.4’’S 60°03’31’’W, 18e 20. ix.2018, Almeida R.P.S. col., ninho em tronco em decomp. Fulakora , Talaridris mandibularis e Pheidole no tronco (1 queen) [ DZUP]. Manaquiri , xi.2009, Winkler, T 1 2/500 (4 workers) [ DZUP]; T1 1/500 (10 workers) [ INPA]; (4 workers) [ DZUP]; T1 3/500 (5 workers) [ INPA]; T2 2/500, (1 worker) [ DZUP]; (10 workers) [ INPA]; T2 3/500 (3 workers) [ INPA]; (2 workers) [ DZUP]; T2 4/500 [ INPA]. Reserva Florestal Adolpho Ducke , 4.ix.1962, W.L. Brown Jr. col., M-169 (5 workers) [ MPEG]; same data, 02°58’89.3’’S 059°57’67.7’’W, 07.xii.2005, TEAM Project, T 1 1/500 (1 worker) [ INPA]; (1 worker) [ DZUP]; T2 3/400 (1 worker) [ INPA]; T4 10/700 (2 workers) [ INPA]; same data, -2.93333 -59.95, 152m, 03.viii.2006, J. Souza & P. Oliveira cols., ANTC10226, pitfall, 8PPBIO Grid, L-O 03, CASENT0179474 (1 worker) [ CASC]; same data, 2°55’43’’S 59°56’46’’W, 08.viii.2004, Baccaro e col., Winkler, TEAM-Acamp. principal, 1m 2 liteira, 2/000, amostra 3, A2-PO-0074 (2 workers) [ INPA]; A2 - PO-0073 (1 worker) [ DZUP]; same data, 24.viii.2005 (2 workers) [ INPA]; 9/300 (1 worker) [ DZUP]; same data, 2°58’45’’S 59°55’13’’W, 24.i.2005, TEAM-Igarapé Ipiranga, 8/700 (1 worker) [ INPA]; A1 - PO-0003 (1 worker) [ INPA]; (1 worker) [ DZUP]; A1 - PO-0020, 8/700 (1 worker) [ DZUP]; A1 - PO-0021 (1 worker) [ DZUP]; same data, 02°58’89.3’’S 059°57’67.7’’W, 07.xii.2005, TEAM project, T1 1/500 (1 worker) [ INPA]; same data, 13.ii.2007; C1 2/600 (1 worker) [ DZUP]; same data, 15.ii.2007, IMA 2 9/300 (1 worker) [ CASC]; same data, 29.xi.2006, T6 1/900 (10 workers) [ INPA]; (2 workers) [ DZUP]. Rio Branco Rd. Km 4 from fork of Amaz. Rte 1, -7.730534 -61.832043, 22.viii.1962, W.L. Brown col., W-292, berlesate, rainforest (1 worker) [ ANIC] . COLOMBIA: Nariño: Barbacoas, 01°21’49’’N 78°04’45’’W, 640m, 25-27.vii.2006, A. Miranda & O. Reyes cols., Winkler (2 workers) [ DZUP]. Territorio Kofán , 00°30’N 77°13’W, 1430m, 25.ix.1998, E. González leg., Winkler, T 2 191(1 worker) [ CEPEC]; same data (1 worker) [ DZUP] .

Figures

FIGURE 23. Holotype worker of Prionopelta minuta (Brazil, Rondônia). A. Full-face view; B. Lateral view; C. Dorsal view. Specimen: DZUP549780.

FIGURE 24. Queen of Prionopelta minuta (Brazil, Amazonas). A. Full-face view; B. Lateral view; C. Dorsal view.

FIGURE 35. Distribution maps for Neotropical Prionopelta species. Black triangles indicate already known species, white circles indicate new species described here. Red symbols indicate the type locality of each species.