Prenolepis, Mayr, 1861

Boudinot, Brendon E., Borowiec, Marek L. & Prebus, Matthew M., 2022, Phylogeny, evolution, and classification of the ant genus Lasius, the tribe Lasiini and the subfamily Formicinae (Hymenoptera: Formicidae), Systematic Entomology 47, pp. 113-151 : 142

Genus group of Prenolepis

Genera included. Euprenolepis, Nylanderia, Paraparatrechina , Paratrechina , Prenolepis, Zatania.

Definition (worker).

1. With characters of Lasiini .

2. Mandible with 4–7 teeth.

3. Palp formula variable: 6,4; 4,4 3,4; 5,3; 4,3; 3,3; 2,3; 2,2 (Note 1).

4. Basal and masticatory mandibular margins usually meeting at a strongly oblique angle.

5. Clypeus modified for reception of labrum (specifically, clypeus with anterolateral notches; Note 1 of Metalasius ).

6. Frontalcarinae conspicuous,> 0.5 × anteroposteriorantennal torulus diameter.

7. Frontal region of head between antennal toruli flat, frontal carinae not raised above toruli.

8. Antenna 11- or 12-merous.

9. Third antennomere usually longer than broad (see Note 3 of Metalasius ).

10. Compound eyes usually at about head midlength, sometimes set posteriorly (see Note 3 of Lasius genus group).

11. Ocelli present or absent.

12. Dorsum of head with standing setae.

13. Mesonotum, metanotum and/or propodeum discontinuous, metanotum usually differentiated (Note 2).

14. Mesopleuron anterodorsal margin, near posterolateral region of pronotum, usually without raised boss nor with narrow or broad groove traversing the mesosternum (Note 5 of Lasius genus group).

15. Metapleural gland very small, orifice directed completely to nearly completely posteriorly (Note 5 of Metalasius ).

16. Propodeal spiracle situated in lower 2/3 of propodeum.

17. Legs with or without standing setae.

18. Petiole with very low node and posteriorly elongated.

19. Abdominal tergum III inclined anteriorly, with deep groove for reception of petiole, concealing most of petiole in dorsal view when gaster raised.

20. Abdominal tergum III with complete tergosternal fusion adjacent to helcium, and fusion raised anterodorsally, with sclerites becoming free high up on segment.

21. Pubescence of abdominal terga VI and VII often dense, forming a uniform layer of short and strongly curved setae (Note 3).

Notes on definition:

Note 1. The palp formula of most genera is 6,4. Most Euprenolepis , however, have a palpomere count of 3,4, with the exception of E. negrosensis (Wheeler), which has a 4,4 count. The count is variable in Pseudolasius , while the count in Paraparatrechina, particularly the weissi species group, is also reduced ( LaPolla et al., 2010).

Note 2. The metanotum of many but not all Paraparatrechina is undifferentiated.

Note 3. These setae may or may not completely cover tergum VI. Absence of this characteristic pubescence occurs in and may be a synapomorphy of Euprenolepis and Paratrechina .

Comments. Paratrechina has recently expanded from a single species to six ( LaPolla et al., 2010, 2013; LaPolla & Fisher, 2014; Williams & LaPolla, 2016). One of these recently added species, P. kohli , was originally described in Prenolepis , transferred to Nylanderia (as a subgenus of Paratrechina ), back to Prenolepis , and finally to Paratrechina (sensu stricto) ( LaPolla & Fisher, 2014). This species stood out from the remainder in its surface sculpturing, eye positioning, color, and mandibular dentition. It was observed during this study that P. kohli has a petiolar node which exceeds propodeal spiracle height, lacks the raised tergosternal fusion of abdominal segment III and posterior elongation of the petiole, and closely resembles species of Anoplolepis , specifically A. carinata (Emery) and A. tenella (Santschi). In addition, P. kohli has 11-merous antennae, an undifferentiated metanotum, posteriorly set eyes, and lacks ocelli, as is characteristic of Anoplolepis ( Fisher & Bolton, 2016) . We find in combined analyses that P. kohli always falls outside of the Lasiini ( Figs 4 , S 7–S 9 ). For these morphological and phylogenetic reasons, we transfer the species P. kohli to Anoplolepis in the Plagiolepidini, forming A. kohli ( Forel, 1916) comb.nov. (tribal transfer). Expanded sampling of male characters may improve placement of the fossil taxon † P. henschei , with respect to the remainder of the genus group.

Figures

Fig. 4. Results from phylogenetic analysis of the Lasiini_w_outgroups_w_fossils_154t combined morphological and molecular dataset analyzed with MrBayes using the fossilized birth-death branch length prior and the IGR clock variation prior. Fossil taxa are indicated by a dagger preceding the name. Node support values are in Bayesian posterior probability. Filled circles indicate full support. Horizontal blue bars at nodes are 95% highest posterior density (HPD) intervals.

Fig. 7. Some key features of the major clades of the Lasiini. (A) third abdominal tergite modified with dorsoventrally-oriented groove for reception of entire petiole (Pseudolasius breviceps); black line indicates contour of tergum and black ellipse the spiracle; (B) third abdominal tergite receiving only posterior base of petiole (Myrmecocystus mimicus); white line indicates contour of tergum, and white ellipse the spiracle; (C) frontal protuberance and effaced carinae low relative to face (P. breviceps); (D) frontal protuberance and effaced carinae raised dorsally from face (M. mimicus); (E) metapleural gland atrium grossly enlarged (Lasius subumbratus); black lines show larger size of the metapleural gland bulla (lower indicator) as compared to F, and relative to the propodeal spiracle (upper indicator) and space between the spiracle and bulla (middle portion); (F) metapleural gland atrium small (Lasius turcicus); black lines show smaller size of metapleural gland bulla as compared to E, and relative to the propodeal spiracle and space between spiracle and bulla.

Fig. 9. Gross phenotypic synopsis of the species groups of Lasius, plus two phenotypically similar fossil species; all images in profile view; scale bars = 1.0 mm; scale bar unavailable for K. (A) Lasius brunneus (CASENT0280440); (B) Lasius fuliginosus (CASENT0179898); (C) Lasius nr. niger (CASENT0106128); (D) Lasius nr. atopus (CASENT0234858); (E) Lasius carniolicus (CASENT0280471); (F) Lasius claviger (CASENT0103542); (G) Lasius brevicornis (CASENT0280456); (H) Lasius nearcticus (CASENT0104774); (I) Lasius pallitarsis (CASENT0005405); (J) Lasius aphidicola (CASENT0280468); (K) †Lasius schiefferdeckeri (HJF013); (L) †Kyromyrma neffi (AMNH-NJ1029). (Image credits: D = the authors; AntWeb: A = Will Ericson; B = Erin Prado; C = Michael Branstetter; E, G, J = Shannon Hartman; F, H = April Nobile; I = unknown; K = Vincent Perrichot; L = Dave Grimaldi & Vincent Perrichot.)