Myrmosidae Fox, 1894

Okayasu, Juriya, Lelej, Arkady S., Williams, Kevin A., Brabant, Craig M., Nguyen, Lien Thi Phuong, Nguyen, Anh Duc, Pham, Thai Hong & Truong, Tuong Thi Cat, 2025, Current knowledge on the velvet ants (Hymenoptera: Mutillidae, Myrmosidae) of Vietnam: faunal review and new distributional records, Zootaxa 5668 (1), pp. 1-104 : 10

Family Myrmosidae Fox, 1894

Myrmosids are morphologically distinct from mutillids ( Krombein 1940; Reid 1941; Kumpanenko et al. 2022; Waldren et al. 2023). The status of this taxon has been controversial ( Brothers & Lelej 2017; Waldren et al. 2023). Previous cladistic frameworks generally treated it as a subfamily of Mutillidae ( Brothers 1975; Brothers & Carpenter 1993; Lelej & Nemkov 1997; Brothers & Lelej 2017). Morphologically, the sister-relationship of Myrmosinae and the remaining mutillid subfamilies is well supported by unique synapomorphies ( Brothers & Lelej 2017). However, recent molecular phylogenetic and phylogenomic analyses often suggest the family-level status of myrmosines ( Pilgrim et al. 2008; Debevec et al. 2012; Branstetter et al. 2017), although the placement of Myrmosidae within Pompiloidea is unstable. With extended taxon sampling and ultraconserved element phylogenomic approach, Waldren et al. (2023) concluded that the full-family status of Myrmosidae was reasonable and well-supported since this taxon was recovered as sister to Sapygidae or Pompilidae + Sapygidae . We followed this treatment and regarded myrmosids as a distinct family, with Kudakrumiinae Krombein, 1979 and Myrmosinae as its subfamilies. See Brothers & Lelej (2017) and Waldren et al. (2023) for further discussion on this issue.

This family was previously considered to be exclusively distributed in the Holarctic Region ( Krombein 1940; Pagliano et al. 2020). In the Oriental Region, myrmosids had previously been recorded from South Asia only and were represented by two kudakrumiine genera, Kudakrumia Krombein, 1979 and Nothomyrmosa Krombein, 1979 ( Krombein 1979; Lelej 2005), except for Taimyrmosa Lelej, 2005 ( Myrmosinae ) which had one species from Taiwan (Lelej 2005). Surprisingly, Williams et al. (2019c) discovered Kudakrumia and the Palaearctic genus Krombeinella Pate, 1947 ( Myrmosinae ) from Thailand and Vietnam. Because myrmosids lack traditional diagnostic features of velvet ants (e.g., felt line on the second metasomal segment), males can be easily confused with tiphiid and thynnid wasps ( Williams et al. 2019c). Therefore, diverse elements of this family might eventually be found after careful examination of Malaise-trap and yellow pan-trap samples from Southeast Asia.