Phylogenetic position of a remarkable new fideliine bee from northern Chile (Hymenoptera: Megachilidae)

Abstract

Fideliine bees are an archaic group with a disjunct distribution mostly restricted to deserts of South America and South Africa. This group was previously thought to be more diverse in Africa than in South America, where only one genus (Neofidelia) comprising five species is known. Here we describe a species belonging to a second South American genus: Xenofidelia colorada Packer gen. et sp.n., from northern Chile. The species is illustrated and its phylogenetic position within Megachilidae is assessed using morphological, molecular and combined data. The 214 character morphological matrix includes 55 new characters with an additional 16 hitherto unexplored for megachilid phylogeny. The molecular dataset is based upon seven nuclear gene sequences, totalling 6439 bp, many of which are published for the first time for particular megachilid taxa. In all analyses, Xenofidelia was found as sister to Neofidelia (endemic to Chile and Peru). It differs from that genus most notably in its short mouthparts, absence of a glossal rod, unmodified female metabasitarsus and an elongate and horizontal dorsal surface of the metapostnotum. Morphological and combined data support a monophyletic Fideliinae (excluding Pararhophites), while molecular data alone failed to recover fideliine monophyly. Dating analyses suggest that Xenofidelia and Neofidelia diverged 34.3–40.6 Ma, indicating that New World fideliines were probably present in arid habitats of South America during the Eocene. This divergence time predates both the main orogenic events that resulted in the formation of the Andean mountains and the origin of hyperarid conditions in the Atacama Desert; it also corresponds to a period prior to the origin of the summer rainfall area in the far north of Chile where the new genus is found. These results support the view that arid habitats have been present continuously in South America since the Eocene. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:EA69BB4A-6F59-4A15-AB44-2A8949E3CF8F.

Brachymelecta Linsley, 1939, previously the rarest North American bee genus, was described from an aberrant specimen and is the senior synonym for Xeromelecta Linsley, 1939

“…Second, describing new taxa (especially higher-level taxa) from single specimens, although sometimes unavoidable, is undesirable. If unavoidable, such nomenclatural acts should be thoroughly justified, for example, within a phylogenetic context for changes proposed at the supraspecific level, preferably with both molecular and morphological support (e.g., as in Packer et al 2017). The inherent problem of describing new taxa from single specimens is that observed differences are assumed to be interspecific (and in the case of new genera also intergeneric), since intraspecific (and in the case of new genera also intrageneric) variation is not known (Wiens & Servedio 2000;Wiens 2007).…”

The relevance of the mesosomal internal structures to the phylogeny of Augochlorini bees (Hymenoptera: Halictinae)

“…We proposed 24 new character statements for the Augochlorini phylogeny based on internal structures of the mesosoma, and they provided a considerable aid to elucidate the relationships of the group when analysed together with external morphological characters. These structures were already demonstrated as useful for reconstructions in various systematic levels, for example Hexapoda (Friedrich & Beutel ), Hymenoptera (Vilhelmsen, ,b; Vilhelmsen, Miko, & Krogmann, ), Apoidea (Melo, ) and Apidae (Packer et al., ; Porto, Almeida et al., ; Silveira, ). Therefore, we conclude that internal characters should be more explored in bee morphological phylogenetics.…”

“…Internal anatomy remains a largely untapped resource for evidence of evolutionary history (Deans, Mikó, Wipfler, & Friedrich, ). For examples of inclusion of characters derived from internal structures, see Packer, Litman and Praz () and Praz and Packer (). Recently, Porto, Almeida et al.…”

“…Internal anatomy remains a largely untapped resource for evidence of evolutionary history (Deans, Mikó, Wipfler, & Friedrich, 2012). For examples of inclusion of characters derived from internal structures, see Packer, Litman and Praz (2017) and Praz and Packer (2014). Recently, found that the different portions of the mesosoma exhibit distinct phylogenetic signals and that these structures are valuable to phylogenetic reconstruction.…”

A Revision of Cresson Pate (Hymenoptera, Apoidea, Bembicidae) with the description of two new species

“…21). This area has yielded many interesting species of Apoidea in recent years, including a new genus of fideliine (Praz and Packer 2017) and a new species of Colletes (Ferrari 2017) as well as its presumptive cleptoparasite, a recently described species of Isepeolus (Packer and Graham 2020).…”