Triepeolus Robertson 1901
Creators: name: Onuferko, Thomas M.
name: Rightmyer, Molly G.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Apidae
Triepeolus

description: Genus Triepeolus Robertson, 1901
Diagnosis for the simplex species group within Triepeolus
Females of the presumably monophyletic T. simplex group are easily recognized by the well-defined trapezoidal or triangular pseudopygidial area, which has reflective (golden/coppery to silvery) setae, and concave apical margin of T5 (Fig. 1; see also photographs in species treatments below, but note the reflective setae are not clearly visible in some images of the pseudopygidial area due to diffused lighting). Females of three other Triepeolus spp. from the Nearctic also have a concave apical margin to T5 but differ in the pseudopygidial area. In two of these— T. dacotensis (Stevens, 1919) and T. mojavensis Linsley, 1939 —the pseudopygidial area has only dark brown/black setae and is poorly differentiated from the rest of T5 (Fig. 2A). The two species are also unusual among Triepeolus in that both lack a well-defined preoccipital carina, which is present at least on the genal area in all other Triepeolus, including the species comprising the T. simplex group. In the third species, T. distinctus (Cresson, 1878), the pseudopygidial area of the female has golden to silvery setae but is more or less rectangular in shape (Fig. 2B). Males of the T. simplex group are not easily recognized as no single morphological feature or unique combination of features has been identified that can be considered diagnostic, not in the external morphology or terminalia. Rightmyer (2004) did not find a character state unique to the simplex species group, represented by T. kathrynae Rozen, 1989, among the 21 morphological characters pertaining to the male S7, S8, or genitalia assessed for 11 markedly different species in the genus. Although several morphological features have been identified as common to males of the T. simplex group, determining conclusively diagnostic features is complicated by the fact that males remain unknown for 31 species of Triepeolus outside the T. simplex and T. verbesinae species groups (see Supp. file 3 for the complete list). In lieu of a diagnosis, a fully illustrated key is presented to enable the identification of males of the T. simplex group among the species of Triepeolus for which the male has been described (i.e., all other species of Triepeolus except those listed in Supp. file 3, for which the key could not be tested).
Key to separate males of the Triepeolus simplex group from other Triepeolus
1. Any of the following (alone or in combination): clypeus with well-defined glabrous midline, which may extend its entire length (Fig. 3A); F2 shorter than F1 (Fig. 4A); mesoscutellum to some extent reddish brown (Fig. 5A); mesopleuron ventrolaterally with dense, long (≥ ½ MOD), erect/suberect, simple or minutely branched setae (Fig. 6A); propodeal triangle mostly covered in dense, appressed pale setae (Fig. 7A); and/or pygidial plate with well-defined basal or subapical transverse ridge (Fig. 8A) ................................................................... most other Triepeolus spp. (not treated herein)
– The following in combination: clypeus without glabrous midline or rarely with ill-defined glabrous midline restricted to upper half (Fig. 3B); F2 as long as or longer than F1 (Fig. 4B); mesoscutellum black (Fig. 5B–D); mesopleuron ventrolaterally at most with sparse, long (≥ ½ MOD), erect/suberect, simple setae (Fig. 6B) in addition to usual appressed, branched setae or only short (<½ MOD), appressed setae (Fig. 6C–D); propodeal triangle mostly to entirely glabrous, with any pale setae usually restricted to small lateral patches (Fig. 7B); and pygidial plate without transverse ridge or rarely with ill-defined basal transverse ridge (Fig. 8B) .................................................................... 2
2. Pro- and mesotrochanters distinctly tuberculate (Fig. 9A) ................................................................. .................................. T. tuberculifer Onuferko, Rightmyer & Roig-Alsina, 2024 (T. simplex group)
– Pro- and mesotrochanters not tuberculate (Fig. 9B–D) .................................................................... 3
3. Both S4 with apical/subapical fringe of dense, long (> 1 MOD), curved, brown setae and S5 with short, straight subapical setae (Fig. 10A) ................................................ T. simplex Robertson, 1903
– S4 with apical/subapical fringe of dense, long (> 1 MOD), curved, coppery to silvery setae (Fig. 10B– D) and/or S5 with long, curved subapical setae (Fig. 10C–D) ......................................................... 4
4. T1 discal patch trapezoidal with semicircular anteromedial projection, apical transverse band conspicuously narrowed sublaterally at posterior corner of discal patch (Fig. 11A). Axilla extending well beyond midlength of mesoscutellum; tip distinctly pointed and hooked (i.e., concave along medial margin), mesally unattached to mesoscutellum for approximately half medial length of axilla (Fig. 5B) [The Bahamas and Cuba] ..................................... T. roni Genaro, 1999 (T. simplex group)
– Mesosoma and metasoma without the combination of features listed above [other regions] .......... 5
5. T1 with basal band of pale tomentum arched, on each side (or each if medially interrupted) continuous with (and indistinguishable from) lateral longitudinal band, such that discal patch triangular, semicircular, or crescent-shaped (Fig. 11B–C) ................................................................................. 6
– Not as above. T1 basal and apical transverse bands (if present, distinct, and joined laterally) with abrupt transition between basal band and lateral longitudinal band (Fig. 11D–E) (at least if transverse bands not effectively mirror images, as in Fig. 11F–H), such that discal patch quadrangular or transversely oblong or elliptic (Fig. 11D–H) .................................................................................... 7
6. Any of the following (alone or in combination): T1 discal patch forming trapezoid or triangle with concave or straight anterolateral sides (basal/lateral band (or patch) of off-white to yellow tomentum on each side (or each) mesally convex or straight) (Fig. 11B); T1–T4 with medially interrupted apical transverse bands (Fig. 11B); and/or S3 with long, curved subapical setae (Fig. 10C) ............ ............................................................................................ other Triepeolus spp. (not treated herein)
– The following in combination: T1 discal patch semicircular or crescent-shaped (basal/lateral band (or patch) of yellow tomentum on each side (or each) mesally concave) (Fig. 11C); T3–T4 and usually also T2 with complete apical transverse bands (Fig. 11C); and S3 with short, straight subapical setae (Fig. 10D) ................................................................................................................. T. simplex group
7. The following in combination: legs to some extent orange (Figs 3B, 6B, 9B–D, 11E); axilla with tip acute and distinctly pointed (Fig. 5C); T1 basal band distinctly interrupted medially or notched posteromedially (Fig. 11E); T2 with complete or medially narrowly interrupted apical transverse band with pair of basomedially strongly convergent anterolateral extensions (except sometimes in T. rhododontus Cockerell, 1921) (Fig. 11E); and T3–T4 with complete apical transverse bands (Fig. 11E) .................................................................................................................. T. simplex group
– Any of the following (alone or in combination): legs entirely dark brown/black (Fig. 11F–G); axilla with tip right angled or obtuse and somewhat blunt if not broadly rounded (Fig. 5D); T1 basal band (if present) not distinctly interrupted medially or notched posteromedially (Fig. 11G); T2–T4 apical transverse bands (if present) interrupted medially (Fig. 11F); and/or that of T2 (if present) without anterolateral extensions (Fig. 11H) or with pair of basomedially weakly convergent, perpendicular, or basolaterally divergent anterolateral extensions (Fig. 11F–G) ..................................................... 8
8. Any of the following (alone or in combination): legs entirely dark brown/black (Fig. 11F–G); mesopleuron densely punctate (i ≤1d) (Fig. 6C); T1 basal (Fig. 11G) and/or apical (Fig. 11G–H) transverse bands (if present) complete; T2–T4 with medially interrupted apical transverse bands (Fig. 11F); and/or that of T2 with pair of well-defined anterolateral extensions (Fig. 11F–G) .......... ............................................................................................ other Triepeolus spp. (not treated herein)
– The following in combination: legs to some extent orange (Figs 6D, 10D, 11C–D); mesopleuron somewhat sparsely punctate (i≤ 3d) (Fig. 6D); T1 with medially interrupted basal and apical transverse bands (Fig. 11D); T2 with complete (Fig. 11C) or medially narrowly interrupted (Fig. 11D) apical transverse band without well-defined anterolateral extensions; T3–T4 with complete apical transverse bands (Fig. 11C–D) ................................................................................. T. simplex group
Distribution of the Triepeolus simplex group
Canada (Ontario to British Columbia) to central Argentina including the Antilles (Fig. 12A).
Included species
Triepeolus alvarengai Moure, 1955
Triepeolus apache sp. nov.
Triepeolus eumeniformis sp. nov.
Triepeolus hirsutus sp. nov.
Triepeolus kathrynae Rozen, 1989
Triepeolus mexicanus (Cresson, 1878)
Included species (continued)
Triepeolus nemoralis (Holmberg, 1886)
Triepeolus obliteratus Graenicher, 1911
Triepeolus oblongimacula sp. nov.
Triepeolus parahirsutus sp. nov.
Triepeolus paucipunctatus sp. nov.
Triepeolus rhododontus Cockerell, 1921 Included species (continued)
Triepeolus roni Genaro, 1999
Triepeolus saturninus Cockerell & Sandhouse, 1924
Triepeolus segregatus (Cockerell, 1900)
Triepeolus shoshone sp. nov.
Triepeolus simplex Robertson, 1903
Triepeolus tuberculifer Onuferko, Rightmyer & Roig-Alsina, 2024
description: Published as part of Onuferko, Thomas M. & Rightmyer, Molly G., 2024, A revision of the simplex species group of the cleptoparasitic bee genus Triepeolus Robertson, 1901 (Hymenoptera: Apidae), pp. 1-106 in European Journal of Taxonomy 950 (1) on pages 7-18, DOI: 10.5852/ejt.2024.950.2643, http://zenodo.org/record/13691805