In their treatment of “paracolletine” bees, particularly the subfamily Neopasiphaeinae Cockerell, 1930 (Hymenoptera: Colletidae Lepeletier, 1841), Engel and Gonzalez (2022) recognized several new subtribes, these seemingly based on the phylogeny of Almeida et al. (2019) (see Melo 2022 for discussion). For the Australian region, Engel and Gonzalez (2022) recorded three subtribes of Neopasiphaeini, Baeocolletina Engel, 2022, Neopasiphaeina Cockerell, 1930, and Phenacolletina Engel, 2022; most of the genera recognized by Engel and Gonzalez (2022) were placed in Neopasiphaeina, the majority of these previously treated as subgenera of Leioproctus Smith, 1853 (Michener 2000, 2007; Maynard 2013; Leijs et al. 2018; Batley 2025), while Phenacolletina was proposed for Phenacolletes Cockerell, 1905.
Baeocolletina was proposed for the genus Baeocolletes Michener, 1965, which was originally described as a subgenus of Leioproctus by Michener (1965) and has subsequently been recognized as such (i.e., Michener 2000, 2007; Leijs et al. 2018). Baeocolletes is a rather distinctive taxon whose members have two submarginal cells in the fore wing, with the first recurrent vein received within the first submarginal cell basal to the first submarginal cross vein (Michener 2007; Engel and Gonzalez 2022); most others have the second submarginal cell receiving the first recurrent vein. Packercolletes Engel, 2022, proposed for Leioproctus idiotropoptera Packer, 2006, was also included in Baeocolletina based entirely on the first recurrent vein also reaching the first submarginal cell at or slightly basal to the first submarginal cross vein (Engel and Gonzalez 2022). Though the placement of Packercolletes within Baeocolletina was tentative, Engel and Gonzalez (2022) did not provide any phylogenetic support for this decision. In fact, the classification of neopasiphaeine bees proposed by Engel and Gonzalez (2022) has been met with some criticisms at the family-group level (i.e., Melo 2022), with some of their proposed genus-group names subsequently treated as synonyms within Leioproctus (e.g., Batley 2025).
Leioproctus idiotropoptera is a very peculiar species and is morphologically very distinct from Baeocolletes. When described, Packer (2006) was unable to place it to subgenus with other Australian Leioproctus with two submarginal cells. Though the long jugal lobe of the hind wing allied it with Leioproctus (Colletellus) Michener, 1965, Packer (2006) indicated that it did not have a ciliate inner hind tibial spur as defined for that subgenus, leading to a couplet ending in either subgenus Filiglossa Rayment, 1959 or Euryglossidia Cockerell, 1910 (see Michener 2000, 2007), neither subgenus with an elongate jugal lobe; Packer (2006) did not suggest an affiliation with subgenus Baeocolletes. Also of note was the very peculiar venation of the fore wing for the male specimen of L. idiotropoptera, the second medial cell very narrow medially due to the second recurrent vein being deeply concave, both recurrent veins separated by only a few vein widths (Packer 2006); the venation of the female was more typical of Leioproctus with two submarginal cells (Packer 2006). It continued to remain unplaced by Maynard (2013).
Leijs et al. (2018) recently revised Leioproctus (Colletellus), describing many new species, though their concept of the subgenus differed significantly from that of Michener (2000, 2007); an additional species was transferred from Euryglossidia to Colletellus by Batley (2025), resulting in L. (Colletellus) claviger Leijs, 2018 being recognized as a junior synonym of L. rejectus (Cockerell, 1905). Leijs et al.’s (2018) key to subgenera of Leioproctus with two submarginal cells separated Colletellus from all others based only on the long jugal lobe, Batley (2025) confirming this as a reliable character; this character alone would seemingly accommodate Packer’s species within Colletellus. Though Leijs et al. (2018) was not cited by Engel and Gonzalez (2022) they did mention L. aberrans Leijs, 2018 (as Colletellus aberrans), a species described in that work which is unusual in that it usually has three submarginal cells instead of two; the subgenera with three submarginal cells were treated previously by Maynard (2013), with a fossil taxon from New Zealand recently described by Engel and Kaulfuss (2025).
Further study of Leijs et al. (2018) may have had important implications for Engel and Gonzalez’s taxon concepts within Neopasiphaeini. Importantly, Leijs et al. (2018) indicated that the ciliate inner hind tibial spur, used in combination with the long jugal lobe of the hind wing (as per Michener 2000, 2007) was not always diagnostic for Colletellus. Leijs et al. (2018) provided a new diagnosis that, in addition to the long jugal lobe and variable inner hind tibial spur structure also accommodated variable fore wing venation and a large, parallel-sided stigma, both of which are also applicable to Packer’s species (see Packer 2006; Engel and Gonzalez 2022). In addition, Leijs et al. (2018) mentioned the convex clypeus and supraclypeal area characteristic to Colletellus which were also used in the key to Australian genera of Neopasiphaeini and the diagnosis for Packercolletes by Engel and Gonzalez (2022), separating Packercolletes from Baeocolletes, the latter which has the clypeus and supraclypeal flattened (Michener 2007; Leijs et al. 2018; Engel and Gonzalez 2022). All but one of the species of Colletellus recognized by Leijs et al. (2018) have two submarginal cells, but members of the subgenus show some variation in wing venation, some species with the first recurrent vein meeting the first submarginal cross vein, thus also resembling L. idiotropoptera.
The placement of L. idiotropoptera within Colletellus, as suggested here, is seemingly consistent with Leijs et al.’s (2018) concept of the subgenus. However, it is a unique taxon known from only three specimens collected in 1998 (Packer 2006), and the modified fore wing and structures of the fore and mid legs of the single known male (Packer 2006, not mid and hind legs as mentioned by Engel and Gonzalez (2022)) are seemingly not present in other species of Colletellus, at least to the same extent (see Leijs et al. 2018). However, other subgenera of Leioproctus contain some members with modified legs (Maynard 1991), or antenna (Maynard 1992), so the morphology of L. idiotropoptera is not unheard of within Leioproctus s. l.
It would likely be possible to extract DNA from these specimens to confirm its position within Colletellus, as proposed here, or perhaps as a distinct subgenus for which Packercolletes would be the available name. Many of the new species of Colletellus described by Leijs et al. (2018) have COI sequences available in BOLD, and the phylogeny of Almeida et al. (2019) used sequences for other subgenera of Leioproctus s. l. and other Neopasiphaeinae. As indicated by Melo (2022), there is still much to resolve in Neopasiphaeinae.