Prionopelta modesta Forel, 1909

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 : 236-239

Prionopelta modesta Forel, 1909

Figures 25–28 , 35C

Prionopelta modesta Forel, 1909: 241 . Lectotype worker (here designated): GUATEMALA, Forel (the top specimen of a pin with 2 workers), CASENT0102527 [MHNG] (examined by images).

Diagnosis. Lateral portion of frons with foveolate sculpturing moderately spaced and conspicuous shiny interspaces appearing as small raised margins. Twelve antennomeres. Posterior margin of subpetiolar process concave.

Worker measurements (n=5). HL 0.50–0.54; HW 0.44–0.48; SL 0.26–0.28; WL 0.54–0.67; PrL 0.24–0.28; PrW 0.22–0.32; PetNL 0.13–0.18; PetW 0.23–0.28; PetH 0.16–0.21; PetL 0.16–0.17; T1L 0.24–0.26; T1W 0.34– 0.39; TL 1.44–1.62; CI 84–88; SI 54–62; PetI 150–200; PetHI 100–123; PetWI 135–175.

Queen measurements (n=4). HL 0.48–0.58; HW 0.44–0.52; SL 0.27–0.30; WL 0.71–0.83; PrL 0.12–0.13; PrW 0.26–0.33; PetNL 0.14–0.16; PetW 0.24–0.29; PetH 0.18–0.23; PetL 0.14–0.20; T1L 0.23–0.33; T1W 0.37–0.45; TL 1.56–1.94; CI 89–91; SI 57–61; PetI 171–181; PetHI 115–128; PetWI 145–171.

Worker description. Body yellow to light brown. Integument covered by deep and dense foveolate sculpturing with conspicuous 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 margin of mandible convex. Clypeus evenly rounded. Twelve antennomeres; apical ones separated by deep constrictions. Eye placed at the head midlength.

Pronotum almost as long as broad. Distance between the propodeal spiracle and the bulla of the metapleural gland corresponding to one spiracular diameter; distance between the propodeal spiracle and the propodeal dorsum corresponding to two spiracular diameters.

Petiolar node as high as long. Subpetiolar process forming a relatively broad lobe, with its anterior and posterior margins subparallel or parallel; posterior margin concave; posteroventral angle obtuse.

Queen. Like workers, with the expected morphology of Prionopelta queens.

Male. Anterior clypeal margin medially rounded; frontoclypeal suture relatively trapezoidal and truncate medially.

Etymology. Unknown.

Distribution ( Fig. 35C ). The species is known from northern Mexico to western Guyana.

Comments. The species was commonly considered as the only Neotropical Prionopelta with dense sculpturing on the head dorsum, giving the appearance of an opaque integument. Although this trait can be currently used to separate P. modesta from the other species occurring in Central America, the densest and deepest sculpturing on head dorsum of all the Neotropical species described in this work belongs to P. minuta , from which P. modesta can be separated by the larger body size and the concave posterior margin of the subpetiolar process.

Prionopelta modesta is mostly distributed through Central America. Hence, the isolated records of the species in Guyana and Colombia are unexpected. We have examined a considerable number of Prionopelta specimens from Panama and Venezuela and we were not able to recognize any P. modesta individuals in these samples. At the same time, the P. modesta specimens from Guyana and Colombia, examined here, fit with the species diagnosis. Thus, further collection records would be useful to better understand the distribution pattern of the species.

Natural history. The species is mainly known from litter and dead wood samples collected in tropical forests; reported at elevations of 50-1840m.

According to observations available in Brown (1960) about several colonies of P. modesta collected at Pueblo Nuevo, Veracruz, Mexico, colonies appear to be split into sections and occupy bits of rotting wood or bark in the leaf litter. The individuals found in these fragments (workers or workers and larvae) could indicate a low level of organization or that the ants could be more or less nomadic. In a “cafeteria” experiment, several live and dead arthropods were offered, but, overall, just a timid response on the workers’ part was observed, with individuals mostly recoiling violently when their antennae came into contact with the potential prey. On the other hand, some specimens were capable of biting, hanging onto, and stinging into immobility somewhat large arthropods. Still, based on these observations, the usual prey may include small centipedes or symphylans, but further examination of nests needs to be done to determine what Prionopelta feeds upon.

Additional material examined (56 specimens). COLOMBIA: Meta: Transecto Sumapaz , 3.8666667 -74.416664, 1120m, 09.viii.1981, T. van der Hammen col., SUM29, CASENT0260467 (1 worker) [ PSWC] . COSTA RICA: Alajuela: 6km E. Monteverde , 10.29897 -84.74932 ± 50m, 980m, 18.v.2014, J. Longino col., #8693-s, ex. sifted leaf litter, wet forest, CASENT0635127 (1 worker) [ DZUP]; CASENT0635130 (1 queen) [ JTLC]; same data, 10°18’N 84°45’W, 950m, 22.viii.1985, #861-s, LACM ENT 142643 (1 worker, 1 queen) [ JTLC]; same data, Rio Peñas Blancas , 10.3167 -84.7167, 800m, 26.iv.1987, J. Longino col., JTL1578, CASENT0039774 (1 worker) [ JTLC] . Limón: Cerro Plátano , 9.87132 -83.23955 ± 10m, 1020m, 16.vi.2015, ADMAC, #Wa-E-03-1-36, ex. sifted leaf litter, cloud forest, CASENT0636747 (1 worker) [ DZUP]; CASENT0636750 (1 queen) [ JTLC]. Res. Biol. Hitoy-Cerere , 9.65238 -83.02206 ± 25m, 530m, 11.vi.2015, ADMAC, #Wm-E-02-1-03, ex. sifted leaf litter, tropical rainforest, CASENT0632088 (1 queen) [ DZUP]; same data, 670m, #Wm-E-02-1-06, CASENT0632089 (1 worker) [ JTLC] . Puntarenas: 10km SW Pto. Jimenez , 8.46553 -83.36928 ± 30m, 240m, 12.iii.2008, J. Longino col., #6197-s, CASENT0601692 (1 worker) [ JTLC] . GUATEMALA: El Petén: Cerro Cahul , 17.00056°N 89.71992°W, 330m, 24.v.2009, J. Longino col., #6683.1, moist forest, ex. dead wood, CASENT0611043 (1 worker) [ JTLC] . Izabal: 16km ESE Morales , 15.41109°N 88.71184°W ± 28m, 440m, 19.v.2009, LLAMA, #Wm-B-04-2-03, ex. sifted leaf litter, 2° lowland rainforest, CASENT0611474 (1 worker) [ DZUP]; CASENT0611473 (1 queen) [JTLC]. GUYANA: Mt. Ayanganna Base Camp , 5.33438 -59.92477, 732m, 09.x.2002, J.S. LaPolla col., JSL021009-03- LS01, litter sample, forest, USNMENT00418417 (1 worker) [ USNM] . HONDURAS: Atlántida: 8km SSW Tela, 15.70961 -87.46828 ± 20m, 360m, 17.vi.2010, LLAMA, #Wm-C-08-2-07, ex. sifted leaf litter, tropical rainforest, CASENT0618691 (1 worker) [ JTLC]; same data, 7km SSW Tela , 15.724667 -87.451935, 190m, 15.vi.2010, #Wa-C-08-2-14, Mini-Winkler, CASENT0618342 (1 queen) [ JTLC] . Comayagua: PN Cerro Azul Meambar , 14.87160 -87.90324 ± 50km, 880m, 21.v.2010, B. Boudinot col., BEB0198, montain rainforest clearing in rotting wood or in soil, CASENT0615797 (1 worker) [ JTLC]; CASENT0615793 (1 male) [ JTLC]; same data, 14.87125 -87.90018 ± 20m, 1120m, 20.v.2010, LLAMA, #Wa-C-04-1-06, ex. sifted leaf litter, ridgetop cloud forest, CASENT0615245 (1 queen) [ JTLC] . MEXICO: Chiapas: 2.8km SE Custepec, 15°43’N 92°56’W, 1840m, 18.vii.2007, R.S.Anderson col., #2007-022, CASENT0602079 (1 worker) [ JTLC]. Laguna Metzabok , 17°08’N 91°38’W, 600m, 14.vii.2007, J. Luna-Cozar col., JTLC000009920 (1 queen) [ DZUP]; JTLC000009933 (1 worker) [ JTLC]. 12mi NW Ocozo- coautla, 3200ft, 04-05.ix.1973, A. Newton col., hojarasca, madera podrida, CASENT0810430 (1 worker) [ MIZA]. 9km SE Santo de Agua , 17°31’N 92°18’W, 50m, 14.vii.2007, R.S. Anderson col., #2007-011, CASENT0602008 (1 worker) [ DZUP]; CASENT0601990 (1 queen) [JTLC]. Nayarit: Isla Maria Madre , 22.vi.1948, M. Cardenas col., #1712, 9076 (9 workers) [ MZSP]; same data, 23.vi.1948 (4 workers) [ MZSP] . Oaxaca: Uluapan , 4km NE Ayautla, 18.06018 -96.64484 ± 200m, 440m, 09.vi.2016, ADMAC, #Wm-F-03-1-03, ex. sifted leaf litter, lowland rainforest, CASENT0640598 (1 queen) [ DZUP]; CASENT0640607 (1 worker) [JTLC]. Veracruz: Est. Biol. Los Tuxtlas, 18.58704 -95.07627 ± 30m, 170m, 31.v.2016, ADMAC, #Ba-F-01-2-04-09, CASENT0640202 (1 worker) [ JTLC]; same data, 18.58625 -95.07665 ± 20m, 180m, 29.v.2016, #Wa-F-01-2-18, ex. sifted leaf litter, tropical rainforest, CASENT0640340 (1 queen) [ JTLC]. Los Tuxtlas, 10km NW Sontecomapan, 18.58333 -95.08333, 200m, 20.iii.1985, P.S. Ward col., PSW07333-11, rainforest, sifted litter (leaf mold, rotten wood), CASENT0260466 (2 workers) [ PSWC]. Sierra Taviscocla above Cuichapa , 04.viii.1965, W.L. Brown col., (9 workers) [ MZSP]. NICARAGUA: Jinotega: Parque Nac. Saslaya , 13.76836 -85.02344 ± 50m, 1060m, 14.v.2011, J. Longino col., #JTL7556, montane wet forest, under rotten wood, CASENT0619506 (1 worker) [ JTLC] . Matagalpa: RN Cerro Musún , 12.96817 -85.23301 ± 20m, 1060m, 02.v.2011, LLAMA, #Wm-D-01-1-07, ex. sifted leaf litter, montane wet forest, CASENT0624190 (1 worker) [ JTLC] .

Figures

FIGURE 25. Lectotype worker of Prionopelta modesta (Guatemala).A. Full-face view; B. Lateral view; C. Dorsal view. Modified from AntWeb.org images by April Nobile, Specimen: CASENT0102527.

FIGURE 26. Worker of Prionopelta modesta (Costa Rica, Limón). A. Full-face view; B. Lateral view; C. Dorsal view. Specimen: CASENT0636747.

FIGURE 27. Queen of Prionopelta modesta (Mexico, Oaxaca). A. Full-face view; B. Lateral view; C. Dorsal view. Specimen: CASENT0640598.

FIGURE 28. Male of Prionopelta modesta (Honduras, Comayagua).A. Full-face view; B. Lateral view; C. Dorsal view. Modified from AntWeb.org images by Will Ericson, specimen: CASENT0615793.

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.