Prenolepis

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Prenolepis
Temporal range: 37.2–0 Ma Middle Eocene – Recent
Prenolepis imparis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Lasiini
Alliance: Prenolepis genus group
Genus: Prenolepis
Mayr, 1861
Type species
Tapinoma nitens, now Prenolepis nitens
Diversity
21 species
1 fossil species
(Species Checklist, Species by Country)

Prenolepis imparis casent0102823 profile 1.jpg

Prenolepis imparis

Prenolepis imparis casent0102823 dorsal 1.jpg

Specimen Label

The genus Prenolepis is a relatively small clade of formicine ants that includes thirteen extant species and one fossil species. While most species are found in southern China and southeastern Asia (11 of the 13 extant species), there is one very widespread species found in North America and a species in southeastern Europe. One fossil species is known from mid-Eocene (ca. 44 Ma) Baltic amber (LaPolla & Dlussky 2010). Within the Formicinae, Prenolepis belongs to a speciose clade known as the Prenolepis genus-group, which includes six other genera: Euprenolepis, Nylanderia, Paraparatrechina, Paratrechina, Pseudolasius, and Zatania (LaPolla et al. 2010a; LaPolla et al. 2012).

Identification

Keys including this Genus

 

Keys to Species in this Genus

Distribution

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 6 1 1 1 9 11
Total Species 2841 1736 3045 932 835 4379 1741 2862

Fossils

Fossils are known from: Baltic amber (Bartonian, Middle to Late Eocene), Bitterfeld amber (Bartonian, Middle to Late Eocene), Danish-Scandinavian amber (Bartonian, Middle to Late Eocene), Rovno amber (Priabonian, Late Eocene), Zhangpu amber, Zhangpu County, Fujian Province, China (Miocene) (an unidentified species, Wang et al., 2021).

Biology

Williams and LaPolla (2016) - Most of what is known about the biology and natural history of Prenolepis comes from what has been observed in the widespread North American species, Prenolepis imparis (sometimes called the false honey ant). The biology of P. imparis is recounted here, but it is not known how general its biology is overall with regards to other species in the genus, and it is important to bear in mind P. imparis is a temperate species whereas most Prenolepis are found in tropical habitats. In P. imparis, colonies are polygynous, but contain relatively small numbers of workers (typically a few thousand workers in a colony) (Wheeler & Wheeler 1986; Tschinkel 1987). The nests of P. imparis are exceedingly deep with no chambers found shallower than 60 centimeters below the ground surface and going down as far as 3.6 m (Tschinkel 1987).

False honey ants are peculiar in that the workers are cold-tolerant and forage during the cooler months when most other ant species are inactive. The colony enters an estivation period and becomes inactive above ground for the warmer months, during which time eggs are laid and brood are reared. Reproductives overwinter and emerge on the first warm day of spring for their nuptial flight. One characteristic of P. imparis colonies is the presence of workers with greatly extended gasters. Corpulents were once believed to be true repletes like those of genus Myrmecocystus (Wheeler 1930a; Talbot 1943) until Tschinkel (1987) determined that their enlarged state is actually caused by hypertrophied fat bodies and not the result of crop distention from retained liquid food. Prenolepis imparis is a generalist omnivore (Wheeler 1930a).

The biology of the European false honey ant (Prenolepis nitens) is similar to that of P. imparis (Lőrinczi 2015), but it remains unclear if other Prenolepis species, all of which are found in the tropics, display similar natural histories. It is worth noting that P. imparis and P. nitens are sister taxa and they may in fact be sister to the rest of the Prenolepis (LaPolla et al. 2012; this study). Across all Prenolepis species most specimens are collected using leaf litter extraction methods such as Berlese and Winkler extractors (LaPolla et al. 2010a). Even though P. imparis and P. nitens are one of the most commonly encountered ants in the temperate North, based on their relative rarity in collections, tropical Prenolepis species appear to be far less common. It is also possible that their biology makes them less likely to be collected using standard collecting methods. For instance, some Euprenolepis and Zatania species are known to be nocturnal. Unfortunately, for most species reproductives have not been collected.

In Singapore, Peeters and Yong (2017) observed Prenolepis subopaca nesting in the leaf litter and foraging arboreally

Association with Other Organisms

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Species Uncertain

  • An unknown species is a host for the cestode Raillietina echinobothrida (a parasitoid) (Quevillon, 2018) (encounter mode secondary; indirect transmission; transmission outside nest).
  • An unknown species is a host for the cestode Raillietina tetragona (a parasitoid) (Quevillon, 2018) (encounter mode secondary; indirect transmission; transmission outside nest).

All Associate Records for Genus

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Taxon Relationship Associate Type Associate Taxon Associate Relationship Locality Source Notes
Prenolepis host cestode Raillietina echinobothrida parasitoid Quevillon, 2018 encounter mode secondary; indirect transmission; transmission outside nest
Prenolepis host cestode Raillietina tetragona parasitoid Quevillon, 2018 encounter mode secondary; indirect transmission; transmission outside nest
Prenolepis henschei host nematode Heydenius formicinus parasite Baltic amber Poinar, 2002 Baltic amber fossil
Prenolepis imparis host fungus Laboulbenia formicarum parasite Quevillon, 2018 encounter mode primary; direct transmission; transmission within nest
Prenolepis imparis host fungus Laboulbenia formicarum pathogen Espadaler & Santamaria, 2012
Prenolepis imparis mutualist aphid Aphis cornifoliae trophobiont Favret et al., 2010; Saddiqui et al., 2019
Prenolepis imparis mutualist aphid Aphis fabae trophobiont Favret et al., 2010; Saddiqui et al., 2019
Prenolepis imparis mutualist aphid Capitophorus elaeagni trophobiont Favret et al., 2010; Saddiqui et al., 2019
Prenolepis imparis mutualist aphid Nearctaphis bakeri trophobiont Favret et al., 2010; Saddiqui et al., 2019
Prenolepis imparis mutualist aphid Rhopalosiphum maidis trophobiont Barton and Ives, 2014; Saddiqui et al., 2019
Prenolepis imparis mutualist aphid Uroleucon sonchellum trophobiont Favret et al., 2010; Saddiqui et al., 2019

Flight Period

All Flight Records for Genus

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Taxon Month Source Notes
Prenolepis imparis Jan Feb Mar Apr May Jun Dec antkeeping.info
Prenolepis nitens Apr May antkeeping.info

Life History Traits

  • Mean colony size: 3370 (Greer et al., 2021)
  • Compound colony type: not parasitic (Greer et al., 2021)
  • Nest site: hypogaeic (Greer et al., 2021)
  • Diet class: omnivore (Greer et al., 2021)
  • Foraging stratum: subterranean/leaf litter (Greer et al., 2021)
  • Foraging behaviour: cooperative (Greer et al., 2021)

Castes

Morphology

Worker Morphology

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• Antennal segment count: 12 • Antennal club: absent-gradual, weak • Palp formula: 6,4 • Total dental count: 6-7 • Spur formula: 1 simple, 1 simple • Eyes: >100 ommatidia • Scrobes: absent • Pronotal Spines: absent • Mesonotal Spines: absent • Propodeal Spines: absent • Petiolar Spines: absent • Caste: none or weak • Sting: absent • Metaplural Gland: present • Cocoon: absent

Karyotype

All Karyotype Records for Genus

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Taxon Haploid Diploid Karyotype Locality Source Notes
Prenolepis imparis 16 Switzerland Hauschteck, 1962
Prenolepis jerdoni 30 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 31 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 32 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 34 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 34 Malaysia Goni et al., 1982
Prenolepis jerdoni 36 Malaysia Goni et al., 1982
Prenolepis jerdoni 16 32 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 20 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 25 Malaysia Imai et al., 1983 B Chromosome
Prenolepis jerdoni 27 Malaysia Imai et al., 1983 B Chromosome

Phylogeny

Formicinae
Myrmelachistini
Lasiini
Melophorini
Formicini
Gesomyrmecini

Gesomyrmex  (7 species, 12 fossil species)

Oecophyllini

Oecophylla  (15 species, 16 fossil species)

Plagiolepidini
Gigantiopini

Gigantiops  (1 species, 0 fossil species)

Santschiellini

Santschiella  (1 species, 0 fossil species)

Myrmoteratini

Myrmoteras  (41 species, 0 fossil species)

Camponotini

See Phylogeny of Formicinae for details.

Nomenclature

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

  • PRENOLEPIS [Formicinae: Plagiolepidini]
    • Prenolepis Mayr, 1861: 52. Type-species: Tapinoma nitens, by subsequent designation of Bingham, 1903: 325.
    • [Type-species not Formica imparis, unjustified subsequent designation by Emery, 1906b: 134, repeated in Wheeler, W.M. 1911f: 171 and Wheeler, W.M. 1922a: 940.]

Williams and LaPolla (2016) - For only two species are all castes known (Prenolepis imparis and Prenolepis nitens); therefore, we provide only a worker-based diagnosis for the genus. The character states for characters 12 (mesonotum with a strong mesonotal depression that gives the appearance of a mesonotal constriction) and 15 (presence of rugae that cross from the mesonotum to the mesopleuron) are assumed to be synapomorphies based on the phylogenetic analysis mentioned above.

1. Monomorphic, medium to large in size (2.4–4.9 mm in total length); ranging from pale yellow to dark brown in color.

2. The head, mesosoma, and gaster are typically covered in erect macrosetae that are thin and wispy. Pairs of erect macrosetae run medially from the clypeus to the posterior margin of the head.

3. Antennae 12-segmented; scapes vary in length among species (SI range 109–214), but they always surpass the posterior margin and most species have a scape index above 130; dense setation on scapes.

4. Eyes medium to large relative to head width (REL2 range 21–49) and placed far posterior to the midline of the head (EPI > 125); eyes convex, sometimes surpassing the lateral margin of the head in full-face view.

5. Mandibles with 5–7 teeth on the masticatory margin; apical tooth the longest, 3rd and 5th tooth from apical reduced and 6th tooth also reduced when 7 teeth are present; in many species the ectal surface of the mandibles has longitudinal striations.

6. Palp formula 6:4.

7. In profile view, the mesonotum in all Prenolepis species is curved and depressed immediately posterior to the pronotum, which gives the appearance of a mesonotal constriction; longitudinal rugae that extend from the mesonotum to the mesopleuron are present at the constriction; mesosoma can be robust as seen in P. nitens, but sometimes much more gracile as seen in Prenolepis subopaca (BLI range 122–206).

8. In profile view, the propodeum is at about the same height or slightly higher than the mesonotum; propodeum is either domed with a rounded dorsal face as seen in Prenolepis naoroji, or obtusely angled with a flat dorsal face as seen in Prenolepis angularis.

9. Mesonotal and metanotal sutures are absent or in complete and shallow.

10. In profile view, petiole is typically forward-inclined and wedge-shaped, but in some species the petiole is elongate with a more rounded dorsal apex of the scale.

11. Legs are elongate (profemur length 0.7–1.5mm).

The constriction of the mesonotum has long been used as a defining characteristic of Prenolepis. However, the mesonotal constriction observed in Prenolepis species is distinct from what has been described as a mesonotal constriction in species from other genera, including the following: Nylanderia emmae, Nylanderia opisopthalmia, Paratrechina umbra, Paraparatrechina pallida, Zatania gibberosa, and Zatania gloriosa. In profile view, all of these species have an elongated mesosoma with a flattened mesonotum. By contrast, the constriction seen in all Prenolepis species is defined by a distinct mesonotal depression immediately posterior to the pronotum and longitudinal rugae that extend from the mesonotum to the mesopleuron. The mesosoma is also not elongate in most Prenolepis species (except Prenolepis jerdoni, and P. subopaca). Understanding the difference between a true mesonotal constriction and an elongated mesosoma (which on first examination can appear to be the same thing) is essential if a species is to be placed in its proper genus. Confusion regarding this distinction has led to species being placed in Prenolepis that did not belong there. Another important morphological feature for determining proper genus placement within the Prenolepis genus-group is differences in mesosomal sutures. All species of Prenolepis, Paraparatrechina, and Zatania have shallow and incomplete mesosomal sutures. The other four genera, Nylanderia (except Nylanderia opisopthalmia, Paratrechina, Pseudolasius, and Euprenolepis, have mesosomal sutures that are deep and complete.

References