Aneuretinae Emery, 1913

Boudinot, Brendon E., 2015, Contributions to the knowledge of Formicidae (Hymenoptera, Aculeata): a new diagnosis of the family, the first global male-based key to subfamilies, and a treatment of early branching lineages, European Journal of Taxonomy 120, pp. 1-62 : 49-50

Subfamily Aneuretinae Emery, 1913

Figs 7A , 15C

Diagnosis

The male of Aneuretus simoni is uniquely identified by the exceedingly long and thin petiolar peduncle and the unpetiolated third abdominal segment. The species is further identified by the following combination of characters: oblique mesopleural sulcus present; seven closed cells present on forewing; jugal lobe absent; abdominal segment IV without cinctus between pre- and postsclerites; abdominal

sternum IX unpronged and edentate; telomere extending anteroventrad basimere. Additional characters for distinguishing A. simoni from the Dolichoderinae and Formicinae are indicated in couplets 19 and 20 above.

Comments

The sole extant member of the Aneuretinae , A. simoni , is restricted to Sri Lanka, and is the survivor of a lineage which has a somewhat diverse fossil record ( LaPolla et al. 2013). The subfamily is of considerable interest as it is sister to the Dolichoderinae ( Brady et al. 2006) . Eight fossil genera are ascribed to the Aneuretinae based on the work of several authors (e.g., Dlussky & Rasnitsyn 2009). Some taxa, based on workers, are definitely members of the Aneuretinae , i.e., † Paraneuretus and † Protaneuretus from Baltic amber (37–42 My; Wheeler 1915; LaPolla et al. 2013), while others are less certain, i.e., † Pityomyrmex (also from Baltic amber, Wheeler 1915; placed in Aneuretinae by Dlussky & Rasnisyn 2009) and † Aneuretellus (Sakhalin amber, 56–59 My; Dlussky 1988; LaPolla et al. 2013). The impression-fossil taxa † Britaneuretus (see Antropov et al. 2014) and † Mianeuretus (see Carpenter 1930) may not be members of the Aneuretinae . Because of the occurrence of definitive aneuretines in Baltic amber, it will be critical to carefully study the reproductives occurring in these fossils to determine whether any may be placed in the Aneuretinae .

Two fossil “aneuretine” taxa are worth discussing specifically. The affinities of † Burmomyrma (~98 My, Burmese amber; Dlussky 1996; LaPolla et al. 2013) and † Cananeuretus (78–19 My, Canadian amber; Engel & Grimaldi 2005; LaPolla et al. 2013) with Aneuretus simoni are uncertain. The description and illustration of † Burmomyrma in Dlussky (1996) provide no characters which support a relationship of the fossil taxon with Aneuretus ; the diagnosis includes one extreme autapomorphy and several characters which are pleisiomorphic for the family or are broadly shared among several subfamilies. The character combination indicated by Dlussky (1996) to assign † Burmomyrma to the Aneuretinae is weak, especially given that Aneuretus has complete (“ancestral”) wing venation while † Burmomyrma lacks almost all vein abscissae. Placement of † Burmomyrma within the Leptanillinae , and indeed other aculeate hymenopteran families, cannot be ruled out. No taxonomic action is taken here, however.

† Cananeuretus , on the other hand, cannot be so easily considered distantly related to the Aneuretinae . The Grassy Lake deposit of Canadian amber includes representatives of the Sphecomyrminae , Ectatomminae , and critically, the Dolichoderinae ( LaPolla et al. 2013) . While the placement of the fossil dolichoderine † Chronomyrmex (see McKellar et al. 2013) in the Leptomyrmecini (sensu Ward et al. 2010) is debatable, co-occurrence of these subfamilies in this deposit suggests the placement of † Cananeuretus is plausible. As the diagnosis of the Aneuretinae provided here and previously ( Wilson et al. 1956; Bolton 2003) is based largely on pleisiomorphic characters, other characters should be considered. For example, future studies of Canadian amber should be sensitive to specific traits occurring in Aneuretus and extant Dolichoderinae . Aneuretus shares, among other characters, a deep median notch on the anterior clypeal margin and fine serrations intercalated among larger denticles on the masticatory mandibular margin, both of which occur in the Tapinomini , the tribe sister to the remaining Dolichoderinae ( Ward et al. 2010) . Reconsideration of the fossil record of Aneuretinae will be valuable for improving our concepts of both the Aneuretinae and Dolichoderinae .

Figures

Fig. 7. A–B. Forewing. A. Ventral view, gyne. B. Dorsal view, male. C–D. Mesosoma, lateral view, male. E–F. Paramere, lateral view, male. — A. Aneuretus simoni (Sri Lanka, CASENT0172259, A. Nobile). B. Nylanderia vividula (U.S.A., CASENT0058918, A. Nobile). C. Apomyrma stygia (Central African Republic, CASENT0086073, E. Prado). D. Anochetus boltoni (Madagascar, CASENT0063847, A. Nobile). E. Dolichoderus validus (Costa Rica, INB0003662427, B. Boudinot). F. Formica pacifica (U.S.A., JTLC000006350, B. Boudinot). Scale bars: A–C, E–F = 0.5 mm, D = 1.0 mm.

Fig. 15. Male representatives of three subfamilies. A, D. Frontal view. B–C, E. Lateral view. — A–B. Pseudomyrmex holmgreni, Pseudomyrmecinae (Paraguay, CASENT0173758, A. Nobile). C. Aneuretus simoni, Aneuretinae, used with permission from Wilson et al. (1956). D–E. Technomyrmex difficilis, Dolichoderinae (Madagascar, CASENT0049968, A. Nobile). Scale bars: A, D = 0.2 mm, B = 1.0 mm, E = 0.5 mm, no scale available for C.