Hylaeus nelumbonis (Robertson, 1890)

Prosopis nelumbonis Robertson, 1890: 318 [♀].

     Lectotype ♀, designated by W.E. LaBerge, in Webb (1980: 113). USA, Illinois, Carlinville, 12 August 1889, by C. Robertson [ANSP, Robertson no. 8997].

Taxonomic notes: Metz (1911: 151) indicated that the ♂ of Hylaeus nelumbonis (Robertson, 1890) also has a ferruginous base of the abdomen but noted that it had not yet been desceibed. The ♂ was described by Mitchell (1960: 67).

Specimens in the syntype series were collected on Nymphaea reniformis and Nelumbo lutea (Robertson, 1890: 318), though floral information was not provided for the lectotype (Webb 1980: 113). Robertson (1929: 146) indicated that the “type” was collected on Nelumbo lutea but did not indicate whether he was referring to the type series (four specimens) or a specific specimen.

Metz (1911: 136) indicated that his P. fossata Metz, 1911 was possibly the same as P. nelumbonis Robertson, 1890; only the female of the latter was described at that time. This was likely due to the female of P. fossata having a ferruginous base of the abdomen (Metz 1911: 136); though not specifically mentioned for the male holotype of H. fossata, it also shares a ferruginous metasomal base. Crawford (1913: 155) subsequently considered P. fossata a synonym of H. nelumbonis which was subsequently followed by Michener (1951: 1051); this synonymy was likely based on Metz’s (Metz 1911: 136) description as having the collar entirely dark and the ferruginous base of the abdomen. T.B. Mitchell (in Krombein 1958: 212) indicated that the female of P. fossata was a specimen of H. ornatus Mitchell, 1951; as the holotype of P. fossata is the male [USNM no. 00534914] and the sexes were incorrectly associated, the latter name hase priority. Both sexes of H. ornatus have the ferruginous colour limited to tergum 1 (Mitchell 1951: 242, 1960: 68) () while in H. nelumbonis, tergum 1 and most of tergum 2 are red (Mitchell 1960: 67), though this may not always be the case (see DNA barcoding section below).

Interestingly Krombein (1958: 212) also determined that the male holotype of P. fossata was a junior synonym of Hylaeus schwarzii Cockerell, 1896, a species that shares the dark collar (Mitchell 1960: 62) but has the metasoma entirely dark (Mitchell 1960: 62). However, the holotype male of H. fossata has tergum 1 ferruginous, or at least not concolourous with terga 2-7, not entirely black. Though Mitchell (1960: 69) indicated both species were closely related, he distinguished them mainly by the colour of the base of the metasoma. The holotype male of P. fossata should be re-examined for morphological consistency with both H. nelumbonis and H. schwarzii to confirm the synonymy of Krombein (1958).

DNA Barcode Index Number (BIN): BOLD:AAX2614

This BIN corresponds to specimens having the collar entirely black (as per H. nelumbonis, and H. schwarzii), and tergum 1 ferruginous (tergum 1 and 2 is what was described for H. nelumbonis (see Mitchell 1960)), or entirely black (as is H. schwarzii). This results support the synonymy of H. schwarzii and H. fossata under H. nelumbonis, though morphological comparison of type material is required.

Distribution in Canada: Romankova 2007 [ON]; Sheffield et al. 2014 [MB]; Normandin et al. 2017 [QC]; Gibbs et al. 2023 [MB].