Opamyrma

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A monotypic genus known from only a few workers and colonies (Opamyrma hungvuong) collected in central Vietnam and southern China (Yamada et al., 2020).

At a Glance • Monotypic  

Identification

See the diagnosis of the tribe Opamyrmini for the identity of this genus.

Opamyrma was described in the Amblyoponinae, based solely upon worker morphology (Yamane et al. 2008), and was subsequently found by Ward and Fisher (2016) to belong to the Leptanillinae based upon phylogenetic inference from 11 nuclear loci. All subsequent phylogenetic inference consistently recovers Opamyrma as sister to the remaining Leptanillinae (Borowiec et al. 2019; Griebenow 2020, pers. obs.). All adult forms lack complete tergosternal fusion in abdominal segment II, a plesiomorphy unique among the Leptanillinae. The presence of weak propodeal lobes (Yamada et al. 2020: 34) is plesiomorphic relative to the Leptanillini, in which the propodeal lobes are absent in the worker caste. The lack of petiolation of abdominal segment III in the worker caste of Opamyrma is also unique among the Leptanillinae but this character state may not be plesiomorphic for the subfamily. The polarity of the proportions of abdominal postsclerites IV relative to V–VI within the Leptanillinae is also unclear. (Griebenow, 2024)

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Keys including this Genus

 

Distribution

Only known from central Vietnam and southern China.

  • Griebenow (2024), Figure 20. Geographical range of Opamyrma. Locality information derived from AntWeb and available literature, visualized with SimpleMappr.

Distribution and Richness based on AntMaps

Species by Region

Number of species within biogeographic regions, along with the total number of species for each region.

Afrotropical Region Australasian Region Indo-Australian Region Malagasy Region Nearctic Region Neotropical Region Oriental Region Palaearctic Region
Species 0 0 0 0 0 0 1 1
Total Species 2839 1735 3036 932 834 4378 1708 2836

Biology

Castes

Known only from the worker caste.

Phylogeny

Leptanillinae
Opamyrmini

Opamyrma  (1 species, 0 fossil species)

Leptanillini

Leptanilla  (61 species, 0 fossil species)

Protanilla  (18 species, 0 fossil species)

See Phylogeny of Leptanillinae for details.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • OPAMYRMA [Leptanillinae]
    • Opamyrma Yamane, Bui & Eguchi, 2008: 56. Type-species: Opamyrma hungvuong, by original designation.
    • Transferred to Leptanillinae: Ward & Fisher, 2016: 690.
    • In Opamyrmini: Griebenow, 2024: 114.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Worker description. Preoccipital carina complete, almost encircling the head slightly before its posterior margin (“poc” in Fig. 4). Venter of head with a distinct and complete median furrow, with each anterolateral corner forming a process (“alc” in Fig. 3). Clypeus posteriorly margined with a distinct continuous carina (“pcc” in Fig. 3); median part of clypeus rather clearly divided into posterior horizontal portion and anterior steep slope; the posterior portion broadly inserted between antennal sockets, extending anteriorly to the level of posterior margin of the sockets; lateral part of clypeus narrow from front to back. Mandibular base with closed trulleum (“trl” in Fig. 3). Labrum on its outer face with at least two rows of peg-like denticles, each with more than 10 denticles (“lpd” in Fig. 3). Eye absent. Frontal lobe absent. Antennal sockets completely exposed in full-face view, directing almost dorsad, located in a large, roundly excavated area whose anterior wall is steep just behind the posterior margin of clypeus; the area not clearly defined posteriorly. Antenna 12- segmented, gradually incrassate from segment II to XII.

Mesosoma elongate, with a single furrow (“msf” in Figs. 6 & 7) which is deep and flexible and separates pronotum from the remaining part of mesosoma. Metapleural gland bulla round, occupying posterior twofifths of ventrolateral part of the pleuron; metapleural trench running below the bulla. Junction of dorsal and posterior faces of propodeum round without any transverse carina; posterior face of propodeum laterally without spines/carinae. Propodeal spiracle situated relatively low on the side of propodeum, near the weak furrow separating metapleuron from lateral side of propodeum. Propodeal lobe present, low and round.

Mid- and hind tibiae each with a reduced barbulate anterior spur (“ats” in Fig. 8) and a well-developed pectinate posterior spur (“pts” in Fig. 8). Pretarsal claws simple, without teeth.

Waist consisting of a single segment (petiole); petiole elongate, narrowly attached to abdominal segment III (gastral segment I), virtually without anterior peduncle; tergo-sternal sutures of petiole present as longitudinal furrows on ventrolateral edges that meet medially at 1/3 length of petiole from the base (“tss” in Fig. 10); the sternite of petiole reduced to a small posteroventral sclerite, bounded by the conspicuous tergo-sternal sutures; petiolar spiracle located anteriorly on the lateral face of petiole at its mid-height.

Gaster very long, laterally compressed, especially in posterior portion, in profile highest at the posterior end of abdominal segment VI (“absg-VI” in Fig. 11). Segment III (“absg-III” in Fig. 11) seen from above longer than broad, narrowed basally, longer than segments IV, V and VI, having a free anterior face above the helcium; anteriormost part of abdominal sternite III (“abs-III” in Fig.11) produced anteriad to the same level as the anteriormost part of tergite III (“abt-III” in Fig. 11). Segment IV with differentiated presternite (“ps-IV” in Fig. 11). Spiracles on segments V–VII concealed by the preceding segments. Segment VII (“absg-VII” in Fig. 11) longest among the segments III–VII. Pygidium (“abt-VII” in Fig. 11) and hypopygium (“abs-VII” in Fig. 11) unarmed.

Etymology

The genus name Opamyrma is an anagram of Apomyrma for the first three letters.

References