Key to New World Eurhopalothrix

This worker key is based on Longino J. T. 2013. A review of the Central American and Caribbean species of the ant genus Eurhopalothrix Brown and Kempf, 1961 (Hymenoptera, Formicidae), with a key to New World species. Zootaxa. 3693:101-151. doi:10.11646/zootaxa.3693.2.1

1

 * Face, dorsal mesosoma, and first gastral tergite covered with uniform ground pilosity of appressed spatulate setae, lacking dif-ferentiated erect or suberect setae projecting above ground pilosity; posterior face of propodeum with broad, rectangular lamella, not differentiated into acute propodeal spine; HW < 0.5 (Argentina) . . . . . Eurhopalothrix bruchi


 * Face, dorsal mesosoma, and first gastral tergite with thin, non-spatulate ground pilosity or, if with conspicuous spatulate ground pilosity, then accompanied by differentiated larger suberect to erect spatulate setae; posterior face of propodeum as above or with distinct acute propodeal spines; HW variable . . . . . 2

2
return to couplet #1
 * Face with well-defined transverse ridge that separates posterior and anterior portions of face, or clypeus with transverse ridge that separates small posterior triangular portion and larger, concave anterior portion . . . . . 3


 * Neither face nor clypeus with transverse ridge . . . . . 5

3
return to couplet #2
 * Transverse ridge on face, not on clypeus . . . . . 4


 * Transverse ridge on clypeus, not on face (Guyana) . . . . . Eurhopalothrix clypeata

4
return to couplet #3
 * Face with 16 large spatulate setae (Brazil) . . . . . Eurhopalothrix depressa


 * Face lacking spatulate setae (Cuba) . . . . . Eurhopalothrix cimu

5
return to couplet #2
 * Larger erect to suberect setae of face 12–20, distinctly differentiated from ground pilosity or grading into and diffi-cult to distinguish from spatulate ground pilosity . . . . . 6


 * Larger erect setae at most 10; ground pilosity thin, distinctly differentiated from erect setae . . . . . 22

6
return to couplet #5
 * Propodeal spines in the form of broad, foliaceous crests that extend down posterior face of propodeum; face and dor-sal surface of scapes covered with ground pilosity of conspicuous, broad appressed spatulate setae . . . . . 7


 * Propodeal spines in form of acute triangles, with a narrow carina extending ventrally; dorsal surface of scapes with spatulate or narrower appressed setae, ground pilosity of face variable . . . . . 8

7
return to couplet #6
 * HW < 0.6, CI 89–97 (Central America) . . . . . Eurhopalothrix pilulifera


 * HW > 0.9, CI > 100 (southern Brazil) . . . . . Eurhopalothrix lenkoi

8
return to couplet #6
 * HW < 0.56; CI 96; ground pilosity conspicuous, spatulate; differentiated erect setae strongly spatulate, as broad as long; first gastral tergite with spatulate setae in double row of 4–5 pairs down the middle, flanked by 2 or 3 additional setae (Trinidad) . . . . . Eurhopalothrix alopeciosa


 * HW > 0.55; CI > 95; other characters variable . . . . . 9

9
return to couplet #8
 * Eye large, about 9 ommatidia across long axis; legs relatively long, hind tibia length about 0.6 HW; angle between anterior and dorsal faces of petiolar node obtuse; first gastral tergite with 4 pairs spatulate setae; ground pilosity of face uni-formly distributed; masticatory margin of mandible with single tooth row (Costa Rica) . . . . . Eurhopalothrix megalops


 * Eye small, 3–6 ommatidia across long axis; legs relatively short, hind tibia length about 0.4–0.5 HW; other charac-ters variable . . . . . 10

10
return to couplet #9
 * Masticatory margin of mandible with double row of teeth, outer series of lower triangular teeth, inner row of 3–4 long, spini-form teeth; promesonotum rugose and puncta obliterated and frons with a distinct raised median carina . . . . . 11


 * Masticatory margin with single row of triangular teeth; promesonotum smooth (and sometimes shining) between dis-tinct puncta and frons without a distinct raised median carina . . . . . 15

11
return to couplet #10
 * Erect setae on face filiform to weakly clavate, not strongly spatulate (Cuba) . . . . . Eurhopalothrix mabuya


 * Erect setae on face strongly spatulate . . . . . 12

12
return to couplet #11


 * Basal lobe of scape strongly developed, SLI > 15 . . . . . 13


 * Basal lobe of scape less developed, SLI < 14 . . . . . 14

13
return to couplet #12
 * Smaller, HW 0.57–0.66; basal lobe of scape more developed, SLI 21–25; color orange; posterior mesonotum lacking pro-nounced longitudinal keel (Honduras to Costa Rica) . . . . . Eurhopalothrix xibalba


 * Larger, HW 0.69–0.83; basal lobe of scape less developed, SLI 15–21; color dark brown; posterior mesonotum with a pro-nounced, short longitudinal keel between the posteriormost pair of spatulate setae (Mexico, Guatemala) . . . . . Eurhopalothrix hunhau

14
return to couplet #12
 * Petiolar peduncle relatively thin in lateral view; head narrower, CI 97–99; size smaller, HW 0.71–0.74 (Guadeloupe, Dominica) . . . . . Eurhopalothrix guadeloupensis


 * Petiolar peduncle thicker; head broader, CI 110–115; size larger, HW 0.83–0.94 (widespread) . . . . . Eurhopalothrix gravis

15
return to couplet #10
 * Promesonotal dorsum with 3 pairs of large, broadly spatulate setae; projecting setae of face prominent, spatulate, of uniform size, strongly differentiated from ground pilosity*; ground pilosity of face more or less uniformly distributed across frons, vertex lobes, and frontal carinae; first gastral tergite with 4 pairs spatulate setae, these of similar size and shape to those on face, distributed in two longitudinal rows . . . . . 16


 * Promesonotal dorsum with 0–2 pairs of filiform to spatulate setae, clearly differentiated from ground pilosity; projecting setae of face as above or differing in size and grading into ground pilosity; ground pilosity of face as above or variously restricted to symmetrical patches on each side of the midline; first gastral tergite with projecting setae variable . . . . . 17


 * singleton from Costa Rica will fail at this couplet and may be a distinct species. See Comments under Eurhopalothrix oscillum.

16
return to couplet #15
 * HW 0.56–0.70; base of propodeal spines relatively broad, grading into broad infradental lamella; propodeal spines relatively longer and close-set, in dorsal view length about one and one-half as long as distance between their bases; color orange brown (widespread) . . . . . Eurhopalothrix bolaui


 * HW 0.78–0.85; base of propodeal spines narrower, more abruptly meeting narrower infradental lamella; propodeal spines rela-tively shorter and separated, in dorsal view length less than or equal to distance between their bases; color darker red brown (Guatemala, Honduras) . . . . . Eurhopalothrix zipacna

17
return to couplet #15
 * Projecting setae on first gastral tergite and mesosomal dorsum stiff but nearly filiform, not spatulate; puncta on first gastral tergite narrower than interspaces, interspaces smooth, giving gaster shiny appearance; face with shallowly-impressed longitudinal median trough that is devoid of ground pilosity, sculpture of trough densely punctatorugose; apex of labrum forming single projecting lobe, not bifid (Costa Rica; intergrades with E. schmidti in Monteverde, Costa Rica) . . . . . Eurhopalothrix ortizae


 * Projecting setae on first gastral tergite and mesosomal dorsum, when present, clearly clavate or spatulate; puncta on first gastral tergite similar to above or often more closely spaced, with interspaces narrower than puncta diameters; face with or without median trough; apex of labrum typically bifid . . . . . 18

18
return to couplet #17
 * Ground pilosity of face more or less uniformly distributed across frons, vertex lobes, and frontal lobes . . . . . 19


 * Ground pilosity of face divided into two patches separated by medial area devoid of ground pilosity . . . . . 20

19
return to couplet #18
 * Ground pilosity of face relatively thin and sparse; face often with pair of spatulate setae on outermost angles of sides of head, such that full complement of projecting setae is often 20; first gastral tergite with 4 pairs projecting spatulate setae (Costa Rica) . . . . . Eurhopalothrix schmidti


 * Ground pilosity of face relatively thicker and denser; face without pair of spatulate setae on outermost angles of sides of head, full complement 18; first gastral tergite with 3 pairs spatulate setae (Honduras to Costa Rica) . . . . . Eurhopalothrix oscillum

20
return to couplet #18
 * Ground pilosity of face ends abruptly in front of anterior row of projecting spatulate setae; posterior border of ver-tex in full-face view with 4 clavate to spatulate setae; petiolar node typically lacking spatulate setae; first gastral tergite always lacking spatulate setae . . . . . 21


 * Ground pilosity of face extends anteriorly beyond anterior row of spatulate setae; posterior border of vertex in full-face view with 6 spatulate setae; posterior border of petiolar node with pair of spatulate setae; first gastral tergite with 0–3 pairs spatulate setae (Costa Rica) . . . . . Eurhopalothrix semicapillum

21
return to couplet #20
 * In full face view, ground pilosity extends evenly to posterolateral margins of vertex lobes; ground pilosity more strongly flattened (Nicaragua to Costa Rica) . . . . . Eurhopalothrix circumcapillum


 * In full face view, ground pilosity fades posterolaterally, becoming obsolete on vertex lobes; ground pilosity rela-tively narrower (Guatemala) . . . . . Eurhopalothrix machaquila

22
return to couplet #5
 * No specialized setae on face, dorsal mesosoma, petiole, postpetiole, and first gastral tergite; clypeus smooth, highly polished and glassy; face uniformly punctate but with the same highly polished integument (southern Brazil, Paraguay) . . . . . Eurhopalothrix spectabilis


 * At least two larger erect to suberect setae on face; other characters variable . . . . . 23

23
return to couplet #22
 * Face with a single pair of erect spatulate setae on a somewhat protruding eminence on the medial vertex; size large, HW > 0.90; first gastral sternite smooth and shiny anteriorly, with prominent median keel (New Guinea, Philippines, multiple Pacific islands east of New Guinea, Costa Rica) . . . . . Eurhopalothrix procera


 * Face setae variable, but face smoothly convex, without median eminence; HW < 0.90; first gastral sternite punctate anteriorly, lacking median keel . . . . . 24

24
return to couplet #23
 * Face usually with a single pair of erect clavate setae on posterior vertex margin (may have 2 pairs in medial cluster, like E. apharogonia); 3 pairs of erect clavate hairs on promesonotum, including pair on anterior pronotum (Florida, Puerto Rico, Dominican Republic) . . . . . Eurhopalothrix floridana


 * Face with 3–5 pairs erect setae on face; mesonotum with 1–3 pairs erect setae, if < 3 pairs, lacking erect setae on pronotum . . . . . 25

25
return to couplet #24
 * Face with 4 or 5 pairs erect setae, arranged as a posteromedial rectangle of 2 pairs flanked anterolaterally by 1 or 2 pairs . . . . . 26


 * Face with 2 or 3 pairs erect setae, arranged in a close rectangle on posteromedian vertex with third pair (if present) on postero-lateral vertexal corners . . . . . 27

26
return to couplet #25
 * Pronotum lacking erect setae; ground pilosity on face extremely thin and sparse, not easily visible (southern Mexico) . . . . . Eurhopalothrix sepultura


 * Pronotum with pair of erect setae; ground pilosity on face flattened, conspicuous (Guatemala) . . . . . Eurhopalothrix vulcan

27
return to couplet #25
 * Face with 3 pairs erect clavate setae, arranged in rectangle on vertex; mesonotum with 2 pairs erect setae (southern Brazil) . . . . . Eurhopalothrix speciosa


 * Face with 2 pairs erect clavate setae, arranged in rectangle on vertex; mesonotum with 1 pair erect setae (El Salvador) . . . . . Eurhopalothrix apharogonia