Hylomyrma dentiloba ( Santschi, 1931 )

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 : 40-43

Hylomyrma dentiloba ( Santschi, 1931)

Figures 30 , 31 , 80D , 81G , 86 (map)

Lundella dentiloba Santschi, 1931: 271 (W). Holotype: PANAMA: France Field, 2.vi.30, [A.] Bierig [leg.], Sammlung[collection] Dr. F. Santschi Kairouan (1W) (CASENT0913528) [NHMB] [examined]. Combination in Hylomyrma by Kempf, 1960: 430.

Diagnosis. Head dorsum with regular and longitudinal striae, mesial striation in part directed to posterior margin and in part anteriorly divergent and posteriorly convergent, interspaces distinguishable; mesosoma covered with regular to irregular and adjacent striae of variable thickness; dorsal margin of petiole discontinuous, dorsum with same striation of mesosoma lateral; subtriangular projection on mesoventral surface of petiole; subpostpetiolar process weak, convex; transverse striae on profemur posterior surface; protibia extensor surface striate; striation on tergum of first gastral segment restricted to base.

Redescription. WORKER (n=4) ( Fig. 30A–C ): HL 0.85 (0.84–0.92); HW 0.76 (0.76–0.84); ML 0.52 (0.52–0.60); SL 0.55 (0.54–0.60); MOD 0.21 (0.21–0.22); PNW 0.55 (0.55–0.62); WL 1.12 (1.10–1.20); PSL 0.15 (0.15–0.16); PL 0.52 (0.52–0.58); PW 0.22 (0.22–0.26); PPL 0.27 (0.27–0.32); PPW 0.32 (0.31–0.34); GL 0.85 (0.85–1.08); TL 4.15 (4.15–4.65); CI 89.70 (89.70–91.30); SI 72.13 (70.23–75); OI 27.87 (25–26.31). Small to midsized. Subopaque integument, except for the shiny gaster. Head, antennae and mesosoma light brown; yellowish leg; brownish petiole, postpetiole and gaster. Thin and mostly unbranched setae, long to midsized, suberect to subdecumbent; few branched setae with 2–3 or multiple short branches of equal size ( Fig. 80D ), specially on gaster.

Head subquadrate; posterior margin straight. Mandible masticatory margin with 5 teeth. Anterior margin of clypeus straight medially, with a pair of small teeth laterally; median area of clypeus with regular and longitudinal striae, being 6–7 thicker striae, interspaces indistinguishable. Frontal triangle with 2–3 striae. Scape short, not reaching head posterior margin; apical antennomere shorter than 3 previous antennomeres together. Frontal carina slightly concave posterior to antennal socket. Eye reniform, midsized, larger diameter with 11 ommatidia. Striae of variable thickness on head dorsum regular to irregular, longitudinal, mesial striation in part directed to posterior margin and in part anteriorly divergent and posteriorly convergent, interspaces indistinguishable. Head lateral and laterodorsal regions with same striation of head dorsum, striae converging to eye margin; anterior part of laterodorsal region with few striae connecting the region posterior to frontal carina with eye margin; gena striate, irregular and semicircular striae circumscribe the torulus, not reaching eye margin, interspaces indistinguishable. Interspaces between striae on head ventral surface distinguishable.

Mesosoma covered with regular to irregular striae, thinner striae (microsculpture) of variable thickness superimposed on thicker striae (macrosculpture), interspaces indistinguishable. Striation assumes multiple directions; transverse striae on pronotum anterior region (DV) continuing on lateral surface in part towards propodeal spine and in part transversely on propodeum; longitudinal striae on posterior region of pronotum and mesonotum. Promesonotal junction indistinct. Metanotal groove distinguishable by a slight depression (LV). Transverse carina inconspicuous. Dorsal margin of mesosoma slightly discontinuous, mesosoma somewhat straight (mesosoma flattened dorsally). Propodeal lobe bidentate; both teeth blunt, dorsal tooth slightly longer than ventral tooth. Propodeal spine short, straight (LV), divergent (DV), sculptured, and shorter than dorsal tooth of propodeal lobe. Procoxa striae of uniform thickness; regular and transverse striae on C2 and C3. Profemur and protibia mostly covered with regular striae, transverse on profemur, longitudinal on protibia.

Dorsal margin of petiole discontinuous. Convex node; regular striae on anterior, lateral and dorsal surfaces, interspaces indistinguishable; interspaces distinguishable on node ventral surface; transverse striae on anterior surface continuing longitudinally on lateral surface; longitudinal striae of variable thickness on dorsal surface. Postpetiole and subpostpetiolar process with regular and longitudinal striae; subpostpetiolar process weak, convex.

First gastral segment striation similar to postpetiole striae; short striae on tergum, shorter than 1 / 2 of postpetiole length; laterobasal region of sternite covered with striation.

QUEEN (first description) (n=4) ( Fig. 31A–C ): HL (0.92–0.95); HW (0.82–0.88); ML (0.54–0.58); SL (0.58– 0.62); MOD (0.24–0.26); PNW (0.75–0.78); WL (1.32–1.38); PSL (0.22–0.24); PL (0.60–0.63); PW (0.27–0.30); PPL (0.32–0.34); PPW (0.39–0.42); GL (1.08–1.12); TL (4.79–4.98); CI (89.13–93.61); SI (68.18–70.73); OI (27.90–30.48). Midsized. Color, pilosity, and some sculpture characters shared with conspecific workers, only slightly larger. Larger diameter of eye with 12–13 ommatidia. Striae of variable thickness, longitudinal, regular to irregular on scutum, going from an anterior central point towards transcutal suture; thinner striae (microsculpture) between thicker striae (macrosculpture). Longitudinal and mostly regular striae of variable thickness on anepisternum and katepisternum, interspaces indistinguishable. Axilla and scutellum with the same sculpturing pattern as scutum. Irregular striae of variable thickness on propodeum, transverse in DV, directed in part to propodeal dorsum and in part to propodeal spine of lateral surface of mesosoma, interspaces indistinguishable. Wings as in Fig. 81G.

MALE Unknown.

Etymology. Dens, - entis (Latin) = tooth; lobus (Latin) and lobos (Greek) = rounded projection or protuberance.

Comments. Hylomyrma dentiloba is similar to H. blandiens , H. jeronimae , and H. macielae . Hylomyrma dentiloba and H. jeronimae are restricted to Central America ( Figs. 84 , 86 ), co-occuring in Barro Colorado Island, Panama, whereas H. blandiens shows a broad distribution in northwestern South America, from Bolivia to French Guiana ( Fig. 84 ), overlapping in part with the area of distribution of H. macielae (south Colombia and the centernorth of Ecuador) ( Fig. 86 ). Hylomyrma dentiloba can be distinguished from H. blandiens (characteristic in parentheses) in the indistinguishable interspaces on head dorsum striation (vs. distinguishable), the straight dorsal margin of mesonotum (vs. convex), the propodeal spine shorter than the dorsal tooth of propodeal lobe (vs. slightly longer), and the striae length on the first gastral segment shorter to the postpetiole length (vs. similar than the postpetiole length). Hylomyrma dentiloba can be distinguished from H. jeronimae in the regular striae on the mesial region of the head dorsum in part directed towards the posterior margin and in part anteriorly divergent and posteriorly convergent (vs. regular to irregular striae and divergent), the drop-shaped eye (vs. reniform), the longitudinal striation on the mesosomal dorsum (vs. striae assuming multiple directions), and the discontinuous dorsal margin of petiole (vs. continuous). Hylomyrma dentiloba can be distinguished from H. macielae in the drop-shaped eye (vs. oval), and the straight dorsal margin of the mesonotum (vs. convex).

In molecular analysis, the specimens of H. dentiloba from Barro Colorado Island were separated into two clusters: ( H. cf. dentiloba sp.1 ( H. plumosa ( H. cf. dentiloba sp.2, H. versuta ))) ( Pierce et al. 2017). After observing the images of H. cf. dentiloba sp.1 (CASENT0636001) from Costa Rica, we understand that this morphospecies is H. jeronimae n. sp. and that H. cf. dentiloba sp.2 is the true H. dentiloba . The voucher specimens of sp.2 still need to be examined. Also, Pierce et al. (2017) stated that H. dentiloba and H. versuta are morphologically identical, being differentiated only in their geographical distribution. The authors use H. dentiloba to refer to H. dentiloba -like material from the Osa Peninsula of Costa Rica south through Panama, and H. versuta for material from the Atlantic slope of Costa Rica northward. However, we found that H. dentiloba (the H. cf. dentiloba sp.2) can be distinguished from H. versuta in the striation with indistinguishable interspaces on the head dorsum (vs. striation with distinguishable interspaces), the mesosoma and petiolar node covered by thinner striae with indistinguishable interspaces superimposed on irregular and thicker striae (vs. thinner striae with indistinguishable interspaces between irregular and thicker striae), the profemur covered with regular and transverse striae weakly marked (vs. predominantly smooth), the protibia mainly covered with regular and weakly marked striae (vs. predominantly smooth), and the shorter striae on tergum of the first gastral segment (vs. longer striae). Hylomyrma dentiloba can be distinguished from H. jeronimae (the H. cf. dentiloba sp.1) as mentioned in the previous paragraph.

Distribution. Hylomyrma dentiloba distribution is restricted to Panama Canal Zone ( Fig. 86 ).

Natural history. The species inhabits sites at elevations from 90 to 100 m. Some specimens were sampled in leaf-litter, which suggests that this species nests between leaves, in fallen logs, rotten wood, or inside natural cavities of the superficial soil layers.

Additional material examined (48 workers, 8 queens): PANAMA: C[anal] Z[one], Barro Colorado I., 27.ii.1976, A. Newton, leaf litter, forest floor (2W) [ MCZC] ; same locality, June-Oct-1943, Zetek -5105, Lot 43- 16534 (9W 3Q) [ USNM] ; same data (2W, one worker covered with gold) ( MZSP67320 ) [ MZSP] ; (1W) [ IHVL] ; (2W 1Q) [ IFML] ; same locality, i.1960, W.L. Brown, E.S. McCluskey, B-43 (2W) [ MCZC] ; (1W) [ MZSP] ; same locality, Apr-May-42, J. Zetek n°4953 (3W) [ USNM] ; (1W) [ CASC] ; same locality, vii.1941, JasZetek n°4852, Lot n°41-20631 (1Q) ( MZSP67321 ) [ MZSP] ; Colón: San Lorenzo, IBISCA, W13115, F3- May 05, T146-19 (2W) [ CEPLAC] ; same data (1W) (MZHY201) [ MZSP] ; same except W13057, F2- May 05, T145-12 (3W) [ CEPLAC] ; W13044, F1 - May 05, T154-50 (3W) ( MZSP67473 , MZHY216) [ MZSP] ; W13090, F2 - May 05, T145-12 (3W) [ CEPLAC] ; San Lorenzo Forest , 30.xii.2004, 9°17′N, 79°58′W, Dejean, Orivel, Corbara, Aberlenc, Leponce, B2, W12585, Winkler (1W) [ CEPLAC] ; same except B1, W12521 (1W 1Q) [ DZSP] ; F3 , W12305 (1Q) [ MZSP] ; Punta de Los Chivos, W. side Gatun Lake, 3km SW Gatun, 100m, 3–9.july.1979, W.L. Brown col., forest (10W 1Q) [ MCZC] ; Gigante Peninsula , 90m, 9.11363 -79.85430 + 1km, june.2010-july.2011, T.P. Sumnicht col., Wet forest , ex leaf litter (1W) (CASENT0643420) [ MZSP] .

Figures

FIGURE 30. Worker of Hylomyrma dentiloba (MZSP67320). A) frontal view; B) dorsal view; C) lateral view. Photos by Ricardo Kawada.

FIGURE 31. Queen of Hylomyrma dentiloba (MZSP67321). A) frontal view; B) dorsal view; C) lateral view. Photos by M.A. Ulysséa.

FIGURE 80. Types of setae found in the species of Hylomyrma. Unbranched setae: A) Hylomyrma adelae, H. blandiens, H. macielae; B) H. immanis; C) H. marielleae. Branched setae: D) H. dentiloba, H. lispectorae, H. mitiae, H. peetersi, H. virginiae; E) H. balzani, H. lopesi; F) H. blandiens, H. jeronimae, H. versuta; G) H. dolichops; H) H. transversa; I) H. longiscapa; J) H. balzani, H. lopesi, H. primavesi, H. reitteri, H. versuta; K) H. plumosa.

FIGURE 81. Queen’s wings. A) Hylomyrma balzani (MZSP67324); B) H. reitteri (MZSP67431); C) H. versuta (MEXICO: VeraCr.: Pueblo Nuevo, nr. Tetzonapa, Aug.14 -53, E.O. Wilson, #221, rain forest [MCZC]); D) H. longiscapa (MZSP67352); E) H. lispectorae (MZSP67348); F) H. adelae paratype (MZSP67316); G) H. dentiloba (MZSP67319); H) H. mitiae paratype (MZSP67402). Venation: costa (C), radial (R), radial sector (Rs), media (M), cubitus (Cu), anal (A), radial-subcosta (R+Sc), media-cubitus (M+Cu), cubitus-anal crossvein (cu-a), first media-cubitus crossvein (1m-cu), radial sector-media 1 (Rs+M1), radial sector-media 2 (Rs+M2), second radial-radial sector crossvein (2r-rs), radial-subcosta (R+Sc), media-first radial sectormedia (M+1rs-m), submarginal 1+2 (2rs-m). Cells: basal (B), sub-basal (BS), discal (D), sub-marginal 1 (SM1), marginal (M), sub-marginal 2 (SM2).

FIGURE 84. Distribution records of Hylomyrma balzani, H. blandiens, H. jeronimae, and H. lispectorae.

FIGURE 86. Distribution records of Hylomyrma dentiloba, H. macielae, H. reginae, H. villemantae, and H. wachiperi.