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Genus: Euprenolepis   Emery, 1906 

Classification:

Taxonomic History (provided by Barry Bolton, 2018)

Extant: 8 valid species

Euprenolepis Emery, 1906b PDF: 134 [as subgenus of Prenolepis]. Type-species: Prenolepis procera, by original designation. AntCat AntWiki HOL

Taxonomic history

Euprenolepis in Camponotinae, Formicini: Wheeler, 1910a PDF: 143.
Euprenolepis in Camponotinae, Prenolepidini: Forel, 1917 PDF: 249.
Genus Euprenolepis references
Emery, 1925d PDF: 223 (diagnosis, catalogue); Chapman & Capco, 1951 PDF: 214 (Asia checklist); Bolton, 1994: 50 (synoptic classification); Bolton, 1995a PDF: 1049 (census); Bolton, 1995b: 189 (catalogue); LaPolla, 2009 PDF: 6 (diagnosis, all species revision, key); LaPolla et al., 2010A PDF: 124 (diagnosis); Cantone, 2017 PDF: 156 (brief male diagnosis)

Distribution:

   (According to curated Geolocale/Taxon lists)   Genus is native to: Australasia, Indomalaya bioregions (based on species list records).

Australasia Region: Papua New Guinea
Indomalaya Region: Borneo, Indonesia, Malaysia, Philippines

Biology:

Euprenolepis procera is known to be a legionary nomad (McGlynn 2012) and a specialist fungivore as described by Witte & Maschwitz (2008):

In a Southeast Asian rainforest habitat, Euprenolepis procera is specialized in harvesting a broad spectrum of naturally growing mushrooms, a nutritionally challenging and spatiotemporally unpredictable food source. While unfavorable to the vast majority of animals, E. procera has developed exceptional adaptations such as a shift to a fully nomadic lifestyle and special food processing capabilities, which allow it to rely entirely on mushrooms.

Further, E. procera invests little energy in nesting, and frequently relocate their nests nocturnally (Witte & Maschwitz 2008):

All of 40 located E. procera colonies nested opportunistically inside preformed cavities, without obvious nest construction. Furthermore, these ants migrated with high frequency. Eight out of 12 field colonies, which were monitored regularly without disturbance, disappeared within a few days (median, 4 days; range, 1–9 days). Three nest relocations were encountered in the field with emigration columns reaching over several meters and sporadic brood caches on the leaf litter surface. Captured colonies varied considerably in size, comprising approximately 500–5,000 workers and up to three queens. Much larger colonies were observed in the field with estimated colony sizes (based on the duration of their emigrations) of up to 20,000 workers or more.

References:

McGlynn, T. (2012) The ecology of nest movement in social insects. Annual Review of Entomology, 57: 291-308.

Witte, V., & Maschwitz, U. (2008) Mushroom harvesting ants in the tropical rain forest. Naturwissenschaften, DOI 10.1007/s00114-008-0421-9

Taxonomic Treatment (provided by Plazi)

Treatment Citation: LaPolla, J. S., 2009, Taxonomic Revision of the Southeast Asian Ant Genus Euprenolepis., Zootaxa 2046, pp. 1-25

Diagnosis of the Genus EuprenolepisHNS Emery

EuprenolepisHNS Emery, 1906: 134, as subgenus of PrenolepisHNS. Type species: Prenolepis (Euprenolepis) proceraHNS, by original description. EuprenolepisHNS in Camponotinae, Wheeler 1910: 143; in Camponotinae, Forel, 1917: 249; as subgenus of PrenolepisHNS, Wheeler 1922: 697; as subgenus of ParatrechinaHNS, Emery, 1925: 223; in FormicinaeHNS, Donisthorpe: 1943: 645; as subgenus of ParatrechinaHNS, Chapman and Capco, 1951: 218; raised to genus and senior synonym of ChapmanellaHNS, Brown, 1953: 6 (here maintained); in FormicinaeHNS, Wheeler and Wheeler,1985: 258; in FormicinaeHNS, Lasinii, Dlussky and Fedoseeva, 1988: 77; in FormicinaeHNS, PrenolepidiniHNS, Hölldobler and Wilson, 1990: 18; in FormicinaeHNS, PseudolasiusHNS genus-group, Agosti, 1991: 296; in FormicinaeHNS, LasiiniHNS, Bolton, 1994: 50; in FormicinaeHNS, PlagiolepidiniHNS, Bolton, 2003: 23, 102.

Worker (minors and majors):

1) Medium sized (measured in this study between 2.9-6.25 mm in total length) yellow to dark brown formicine ants.

2) E. proceraHNS known to be polymorphic with a minor and major worker castes, unclear if other species are also polymorphic.

3) Antennae 12 segmented; torulae widely separated from each other, not touching posterior clypeal margin.

4) Scapes long, always surpassing posterior margin, and with scattered erect setae.

5) Eyes generally large (one known exception E. negrosensisHNS), near midline of head.

6) Mandibles broad with 5 teeth; basal tooth with an obtuse angle on the inner mandibular margin (one known exception E. negrosensisHNS, where basal tooth is usually roughly quadriform relative to inner mandibular margin); apical tooth large and curved toward midline of body (fig. 1A).

7) Mandalus large and conspicuous (fig. 1A).

8) Maxillary palps 3-segmented; labial palps 4-segmented (except in E. negrosensisHNS which has 4 segmented maxillary palps).

9) Clypeus broad, slightly convex medially, flattening anteriorly; median clypeus without a prominent keel.

10) Anterior clypeal margin medially emarginate, with a medially placed seta.

11) Mesosoma elongate with mesothorax constricted immediately behind pronotum; propodeum high and domed-shaped.

12) Scattered erect setae across entire body.

FIGURE 1. Euprenolepis proceraHNS: A) mandalus indicated by arrow (worker mandible); B) penis valve.

Queen (queens are only known from three species, E. negrosensis,HNS E. proceraHNS, and E. witteiHNS sp. nov. , so this list must be considered provisional):

1) Generally as in worker with modifications expected for caste.

2) Eyes large; ocelli well developed and prominent.

3) Body covered in a dense layer of pubescence.

Male (males are only known from three species, E. negrosensis,HNS E. proceraHNS, and E. witteiHNS sp. nov. , so this list must be considered provisional):

1) Eyes large, occupying more than half the lateral portion of the head; ocelli prominent.

2) Scapes long, surpassing posterior margin by at least first 3 funicular segments; 13-segmented antennae.

3) Anterior clypeal margin emarginate, as in workers; margin curls up slightly.

4) In E. proceraHNS, and E. witteiHNS mandibles broad with only apical tooth well-developed, remainder of inner mandibular margin smooth, with a distinct basal angle. In E. negrosensisHNS, mandibles broad, with 4 teeth; all but apical teeth are weakly developed.

5) Mesosoma modified as expected for flight muscles; propodeum indistinct.

6) In E. proceraHNS and E. witteiHNS, penis valve apodemes terminate dorsally (fig. 1B); in lateral view, penis valves project dorsally above parameres; digiti anvil-shaped (weakly anvil-shaped in E. negrosensisHNS), ventrally directed.

7) Digiti and cuspi meet dorsolaterally, about halfway along length of digiti.

8) Parameres and terminal gastral segments with abundant, long setae; apices of parameres bend towards the midline of the body.

Discussion

Six diagnostic characters can generally separate EuprenolepisHNS workers from the workers of other formicine genera: 1) basal tooth with a distinct obtuse angle on the inner mandibular margin, 2) apical tooth large and curved toward midline of body, 3) mandalus large and conspicuous (fig. 1A), 4) medially clypeus without a prominent keel, 5) anterior clypeal margin medially emarginate, with a medially placed seta, and 6) widely spaced torulae. The reduced segmentation in the palps also helps in diagnosing the genus, except PseudolasiusHNS also exhibits palpal segment reduction. With the exception of E. negrosensisHNS, all species appear to have a 3:4 palpal formula. PseudolasiusHNS typically possess 2 or 3 labial palpal segments. EuprenolepisHNS is most likely to be confused with PseudolasiusHNS, however, with the exception of E. negrosensisHNS, EuprenolepisHNS have much larger eyes than PseudolasiusHNS species. Additionally, the six characters listed above provide a means to separate the two genera. Work in progress (LaPolla, et al., in prep) will provide a key to separate EuprenolepisHNS from close formicine relatives.

E. negrosensisHNS placement within the genus remains somewhat problematic, although the discovery of the males of this species does help clarify the situation (see below). The species was originally placed in its own genus, ChapmanellaHNS, by Wheeler (1930), but overall its general morphology suggest placement in EuprenolepisHNS. However, it is distinctly unlike other species, in that it possesses very small eyes, extreme elongation of the mesosoma, a quadriform basal tooth (although rarely some specimens observed have a basal tooth as in other EuprenolepisHNS species), and a 4:4 palpal formula. This species is at present maintained in EuprenolepisHNS, but this result should be confirmed with molecular data once specimens become available for molecular study.

Morphological characters of E. negrosensisHNS males do suggest placement within the genus for there are several shared characters among the three species where males are known. Among those characters shared with other EuprenolepisHNS males are: 1) digiti weakly anvil-shaped, ventrally directed, 2) digiti and cuspi meeting dorsally, about halfway along length of digiti, and 3) apices of parameres bending towards the midline of the body. These three characters may represent diagnostic features for the genus. Another distinctive feature of all known EuprenolepisHNS males is their hirsuteness, especially on the parameres and terminal gastral segments. The parameres can be difficult to see because of the presence of abundant, long setae. It appears E. negrosensisHNS is a hypogaeic species based on its small eyes and yellow, thin cuticle, and this may explain the unusual appearance of the workers compared to other species within the genus.

It remains unclear how widespread polymorphism is in the genus. Polymorphism is exhibited in E. proceraHNS, with a minor and major worker caste clearly expressed. However, in no other known species is polymorphism observed. This may reflect collecting bias, because most species are only known from a few localities. However, at least one species, E. witteiHNS, has been collected from long nest series and polymorphism has not been found in the workers (V. Witte, pers. comm.). It is worth pointing out that despite E. proceraHNS being by far the most commonly encountered EuprenolepisHNS in collections, majors are still relatively uncommon. Based on the relatively minor morphological differences (other than size) observed between E. proceraHNS minors and majors, it would appear that even if majors are subsequently found in other species the provided key should still work for species-level identifications.

Distribution of EuprenolepisHNS

EuprenolepisHNS is endemic to southeastern Asia (fig. 2). Most species are presently known from Borneo only, but whether or not this reflects biological reality or collecting bias remains unclear. It is interesting to note that this distribution pattern is essentially the same as CladomyrmaHNS, another Southeast Asian endemic formincine genus (Agosti, 1991).

Synopsis of EuprenolepisHNS species

E. echinataHNS, sp. nov.

E. maschwitziHNS, sp. nov.

E. negrosensisHNS (Wheeler, W.M., 1930: 42)

E. proceraHNS (Emery, 1900: 699)

= E. antespectansHNS (Forel, 1913: 130), SYN. NOV.

E. thrixHNS, sp. nov.

E. variegataHNS, sp. nov.

E. witteiHNS, sp. nov.

E. zetaHNS, sp. nov.

FIGURE 2. Distribution of EuprenolepisHNS species.

Names excluded from EuprenolepisHNS

Paratrechina helleriHNS (Viehmeyer, 1914), COMB. NOV

Prenolepis (Euprenolepis) helleri, ViehmeyerHNS, 1914: 41 (worker, queen and male described). Syntype workers, PAPUA NEW GUINEA [New Guinea]: Sattelberg (MCZC; MNHG; NHMB) [7 syntype workers examined]. Emery, 1925: 224, combination in ParatrechinaHNS; Bolton, 1995: 189, combination in EuprenolepisHNS; Bolton et al., 2006, in EuprenolepisHNS.

Paratrechina steeliHNS (Forel, 1910), COMB. NOV

Prenolepis (Nylanderia) steeli, ForelHNS, 10: 69 (worker). Syntype workers, Nauru Island, June, 1908 (F.W. Steel) (MNHG) [2 syntype workers examined]. Emery, 1925: 224, combination in ParatrechinaHNS; Bolton, 1995: 189, combination in EuprenolepisHNS; Bolton et al., 2006, in EuprenolepisHNS.

Paratrechina stigmaticaHNS, (Mann, 1919), COMB. NOV

Prenolepis (Nylanderia) stigmaticus, MannHNS, 1919: 367. Syntype workers, SOLOMON ISLANDS: San Cristoval, Wai-ai (USNM) [syntype worker examined]. Emery, 1925: 221, combination in Paratrechina (Nylanderia)HNS; Donisthorpe, 1941: 42, combination in EuprenolepisHNS; Bolton, 1995: 189, in EuprenolepisHNS; Bolton et al., 2006, in EuprenolepisHNS.

Key to EuprenolepisHNS workers

(As E. proceraHNS is the only known polymorphic species, this key is designed for the minor caste. If majors are subsequently discovered for other species this key should still work, however, if appropriate adjustments for size are made to accommodate majors. For this reason I have not used measurements as a basis to distinguish between species, except where necessary to do so. Based on differences observed between E. proceraHNS majors and minors it appears as if most basic worker level diagnostic characters are retained in both castes). The funiculus is here defined as the part of the antennae minus the scape and condylar bulb and neck.

1 Scapes very long, surpassing posterior margin by about length of the entire funiculus (SI greater than 200); eyes highly reduced (EL no more than 0.05 mm); pronotum and mesonotum greatly elongated, with pronotal width about the same as mesonotal width....................................................................................................................... negrosensisHNS

- Scapes long, but surpassing posterior margin by much less than length of the entire funiculus (SI less than 200); eyes not reduced (EL greater than 0.1 mm); pronotum and mesonotum, if elongated, with pronotal width greater than mesonotal width........................................................................................................................................................... 2

2 Head, mesosoma, and gaster dark-brown; head and mesosomal dorsum covered with a dense network of reticulate rugulae............................................................................................................................................................... proceraHNS

- Head, mesosoma, and gaster brown to yellow; head and mesosomal dorsum not covered with dense network of reticulate rugulae.......................................................................................................................................................... 3

3 Gastral dorsum with a layer of pubescence underneath erect setae.............................................................................4

- Gastral dorsum without a layer of pubescence underneath erect setae........................................................................ 5

4 Gastral dorsum with a dense layer of pubsecence found on segments 1-3 (fig. 10B); from dorsum pubescence extends lateroventrally .......................................................................................................................................... thrixHNS

- Gastral dorsum with a scattered layer of pubescence found predominantly on segment 1 (fig. 14B); pubescence does not extend lateroventrally....................................................................................................................................... zetaHNS

5 Scapes without pubescence; 2nd gastral tergite with two distinct rows of four erect setae (8 long erect setae present on 2nd gastral tergite); eyes more rounded in shape and notably convex in full frontal view; overall dull yellow in color ......................................................................................................................................................................... echinataHNS

- Scapes with pubescence; 2nd gastral tergite with more than 8 long erect setae and these not arranged in distinct rows; eyes more oval in shape and more flattened in appearance in full frontal view; overall shiny brown to yellow in color ...................................................................................................................................................................................... 6

6 In profile, pronotal margin linear as it rises towards mesonotum (fig. 4A); gaster yellow......................... maschwitziHNS

- In profile, pronotal margin rounded as it rises towards mesonotum (figs. 11A and 12A); gaster brown to yellowish-brown........................................................................................................................................................................... 7

7 Gastral setae longer (compare to fig. 11B); majority of gastral setae greater than 0.1 mm in length, with longest setae greater than 0.13 mm in length; overall brownish-yellow, with mesosoma lighter than head and gaster...... variegataHNS

- Gastral setae shorter (compare to fig. 12B); majority of gastral setae less than 0.05 mm in length, with longest setae not exceeding 0.1 mm in length; overall brownish, with pronotum same color as head and gaster, with the propodeum lighter in color............................................................................................................................................ witteiHNS



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