Hylomyrma columbica ( Forel, 1912 )

Ulysséa, Mônica Antunes, 2021, Taxonomic revision of the Neotropical ant genus Hylomyrma Forel, 1912 (Hymenoptera: Formicidae: Myrmicinae), with the description of fourteen new species, Zootaxa 5055 (1), pp. 1-137 : 34-37

Hylomyrma columbica ( Forel, 1912)

Figures 27 , 28 , 85 (map)

Pogonomyrmex (Hylomyrma) columbicus Forel, 1912: 16 (W). Holotype: COLOMBIA: [Magdalena: Sierra Nevada de Santa Marta, Road between Dibulla and] San Antonio, A. Forel (1W) (CASENT0907676) [MHNG] [examined]. Combination in Hylomyrma by Kempf, 1973: 234.

Diagnosis. Regular and longitudinal striae on head dorsum, mesial striation in part directed to posterior margin and in part anteriorly divergent and posteriorly convergent; irregular to regular striae of variable thickness on mesosoma dorsum, interspaces indistinguishable; mesonotum and metanotal groove region with semicircular striae; dorsal margin of petiole discontinuous, transverse striae on anterior region of dorsal surface continuing on lateral surface; subtriangular projection on mesoventral surface of petiole; subpostpetiolar process weak, convex; transverse striae on profemur posterior surface; protibia extensor surface striate; long striae on tergum of first gastral segment.

Redescription. WORKER (n=4) ( Fig. 27A–C ): HL 0.92 (0.92–1); HW 0.89 (0.89–0.94); ML 0.56 (0.56–0.62); SL 0.59 (0.59–0.70); MOD 0.21 (0.21–0.24); PNW 0.62 (0.62–0.66); WL 1.19 (1.19–1.26); PSL 0.22 (0.22–0.24); PL 0.57 (0.54–0.60); PW 0.26 (0.24–0.26); PPL 0.32 (0.32–0.36); PPW 0.35 (0.35–0.36); GL 0.91 (0.91–1.08); TL 4.50 (4.50–4.86); CI 96.47 (94–97.91); SI 65.85 (65.85–74.46); OI 24.39 (24.39–26.66). Small-sized. Shiny integument. Brownish body, yellowish appendices. Thin and unbranched setae, long to short, suberect to subdecumbent.

Head subquadrate; posterior margin straight. Mandible masticatory margin with 6 teeth. Anterior margin of clypeus straight medially, with a pair of small teeth laterally; median area of clypeus with 8–10 regular, longitudinal and thick striae, interspaces between thicker striae filled with thinner striae. Fontal triangle with 1 sagittal stria. Scape short, not reaching head posterior margin; apical antennomere with equal length or slightly shorter than 3 previous antennomeres together. Frontal carina slightly concave posterior to antennal socket. Eye drop-shaped, midsized, larger diameter with 12 ommatidia. Regular and longitudinal striae on head dorsum, mesial striation in part directed to posterior margin and in part anteriorly divergent and posteriorly convergent/parallel, interspaces between thicker striae filled with thinner striae. Striae of variable thickness on head lateral and laterodorsal regions converging to eye margin, interspaces indistinguishable; gena striate, 6–7 regular and semicircular striae circumscribe the torulus, almost reaching eye margin. Interspaces between striae on head ventral surface distinguishable.

Irregular to regular striae of variable thickness on mesosoma dorsum, interspaces indistinguishable; striae assume multiple directions; transverse striae on pronotum anterior region (DV) continuing on lateral surface; pronotum posterior region, mesonotum, and metanotal groove region (immediate anterior to transverse carina) with semicircular striae; part of the irregular striae on mesepisternum continuing on propodeum, and part is directed to propodeal spine. Promesonotal junction and metanotal groove indistinct. Transverse carina well-marked. Dorsal margin of mesosoma continuous, convex. Propodeal lobe bidentate, dorsal tooth longer and acute than the shorter and blunt ventral tooth; dorsal tooth length 1 / 2 of propodeal spine length. Propodeal spine midsized, straight (LV), divergent (DV), sculptured on base. Thin striae of uniform thickness on procoxa; irregular and transverse striae on C2 and C3. Profemur covered with irregular to regular transverse striae. Protibia extensor surface entirely covered with regular and longitudinal striae.

Dorsal margin of petiole discontinuous. Subtriangular projection on mesoventral surface of petiole. Convex node; striae of variable thickness, interspaces indistinguishable; regular and transverse striae on anterior surface and on anterior region of dorsal continuing on lateral surface, striae weakly marked; middle and posterior regions of dorsal surface with longitudinal striae; transverse striae on ventral surface weakly marked. Postpetiole and subpostpetiolar process with regular and longitudinal striae; subpostpetiolar process weak, convex.

First gastral segment striation similar to postpetiole striae; long striae on tergum, longer than postpetiole length; sternite striation covering the laterobasal region.

QUEEN (first description) (n=1) ( Fig. 28A–C ): HL 0.96; HW 0.92; ML 0.60; SL 0.66; MOD 0.27; PNW 0.78; WL 1.38; PSL 0.28; PL 0.62; PW 0.28; PPL 0.38; PPW 0.42; GL 1.18; TL 5.12; CI 95.83; SI 71.74; OI 29.34. Midsized. Color, pilosity, and some sculpture characters shared with conspecific workers, only slightly larger. Larger diameter of eye with 15 ommatidia. Longitudinal and regular striae of variable thickness on scutum going from an anterior central point towards transcutal suture, interspaces between thicker striae filled with thinner striae. Longitudinal striae of uniform thickness on anepisternum and katepisternum, interspaces indistinguishable. Longitudinal and mostly regular striae on axilla, interspaces indistinguishable. Scutoscutellar sulcus inconspicuous. Scutellum with the same sculpture as scutum. Transverse striae on propodeum (DV), interspaces indistinguishable. Lateral surface of mesosoma with mostly regular striae directed in part to propodeal dorsum and in part to propodeal spine, interspaces indistinguishable. Wings unknown.

MALE Unknown.

Etymology. The name is in reference to the species type locality, Colombia.

Comments. The sculpture on the mesosomal dorsum of H. columbica is similar to H. dolichops and H. montana . Hylomyrma columbica differs from H. dolichops (characteristic in parentheses) in the regular striae on the mesial region of head dorsum in part directed to posterior margin and in part anteriorly divergent and posteriorly convergent/parallel (vs. vermicular and divergent striae on anterior two-third of mesial area, irregular and parallel on the upper third), and the drop-shaped eye (vs. reniform). Hylomyrma columbica can be distinguished from H. montana in the combination of the regular striae on the mesial region of head dorsum in part directed to the posterior margin and in part anteriorly divergent and posteriorly convergent/parallel (vs. regular to irregular striae and divergent), the discontinuous dorsal margin of petiole (vs. continuous), and the long striae on tergum of the first gastral segment (vs. short striae). All three are allopatric in northwestern South America, but occur in nearby areas near the border between Colombia and Ecuador. Hylomyrma dolichops has a broader distribution ( Brazil, Colombia, Ecuador, and Venezuela) ( Fig. 87 ), whereas H. columbica occurs in Colombia and in western Venezuela ( Fig. 85 ), and H. montana has been recorded in Costa Rica, Panama and Ecuador ( Fig. 83 ).

Distribution. This species is only known from Colombia and western Venezuela ( Fig. 85 ).

Natural history. Specimens are frequently found in leaf-litter samples with winkler extractors or Berlese-Tüllgren funnels, which suggests that this species nests in the leaf-litter, fallen logs, rotten wood, or inside natural cavities of the superficial soil layers. Also, two specimens were found among plant fibers, which were sourced from Colombia, in a quarantine station in the USA, suggesting that workers may forage on vegetation.

Additional material examined (12 workers, 1 queen): COLOMBIA: on fiber plant from Colombia at Quarantine, Washington DC, 27July1916, E.R. Sasscer collector (2W, one covered with gold) [ USNM] ; Huila: 4k NE Rivera, 30Dec1986, W. Mackay, pitfall trap, forest area, #9039 (1W) ( MZSP67315 ) [ MZSP] ; [La] Guarija : R. Don Diego, 25–50m, 18.june.1976, W.L. Brown & R.C. Kugler [leg.], forest leaf litter (3W 1Q) [ MCZC] ; Mag.[Magdalena]: Pueblito - limite sur, Parque Tayrona, 210–360m, 26.i.78, C. Kugler col., berlese (1W) [ MCZC] ; Pueblito, Tayrona PK., 360m, 11.xi.76, R.C. Kugler & W.L. Brown cols., leaf litter (1W) [ MCZC] ; Meta: 1km E. La Macarena, Caño Morrocoy, 260m, 12.jan.77, C. Kugler col., litter berlesate (1W) [ MCZC] ; same except 25.iv.1976 (1W) [ MCZC].

VENEZUELA: Zulia: El Tucuco , Dto. Perijá, 6.ix.1984, cols. J. L attke, E. Rubio (1W) (MZHY192) [ MZSP]; 54km ESE Yaracal, Falcon, 935m, Cerro Los Caracoles, 10.8718 –69.0274 °, 24.iii.2002, J. Lattke, 2482 (1W) [ DZUP] .

Figures

FIGURE 27. Worker of Hylomyrma columbica (COLOMBIA: on fiber plant from Colombia at Quarantine, Washington DC, 27July1916 [USNM]). A) frontal view; B) dorsal view; C) lateral view. Photos by Ricardo Kawada.

FIGURE 28. Queen of Hylomyrma columbica (COLOMBIA: [La] Guarija: R. Don Diego, 25-50m, 18.june.1976, forest leaf litter, W.L. Brown & R.C. Kugler [leg.] [MCZC]). A) frontal view; B) dorsal view; C) lateral view. Photos by M.A. Ulysséa.

FIGURE 83. Distribution records of Hylomyrma adelae, H. dandarae, H. longiscapa, H. montana, and H. sagax.

FIGURE 85. Distribution records of Hylomyrma columbica, H. marielleae, H. plumosa, and H. reitteri.

FIGURE 87. Distribution records of Hylomyrma dolichops, and H. mitiae.