Comprehensive Description

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Diagnosis of the Genus Euprenolepis HNS Emery

Euprenolepis HNS Emery, 1906: 134, as subgenus of Prenolepis HNS . Type species: Prenolepis (Euprenolepis) procera HNS , by original description. Euprenolepis HNS in Camponotinae, Wheeler 1910: 143; in Camponotinae, Forel, 1917: 249; as subgenus of Prenolepis HNS , Wheeler 1922: 697; as subgenus of Paratrechina HNS , Emery, 1925: 223; in Formicinae HNS , Donisthorpe: 1943: 645; as subgenus of Paratrechina HNS , Chapman and Capco, 1951: 218; raised to genus and senior synonym of Chapmanella HNS , Brown, 1953: 6 (here maintained); in Formicinae HNS , Wheeler and Wheeler,1985: 258; in Formicinae HNS , Lasinii, Dlussky and Fedoseeva, 1988: 77; in Formicinae HNS , Prenolepidini HNS , Hölldobler and Wilson, 1990: 18; in Formicinae HNS , Pseudolasius HNS genus-group, Agosti, 1991: 296; in Formicinae HNS , Lasiini HNS , Bolton, 1994: 50; in Formicinae HNS , Plagiolepidini HNS , 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. procera HNS 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. negrosensis HNS ), 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. negrosensis HNS , 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. negrosensis HNS 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 procera HNS : A) mandalus indicated by arrow (worker mandible); B) penis valve.

Queen (queens are only known from three species, E. negrosensis, HNS E. procera HNS , and E. wittei HNS 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. procera HNS , and E. wittei HNS 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. procera HNS , and E. wittei HNS mandibles broad with only apical tooth well-developed, remainder of inner mandibular margin smooth, with a distinct basal angle. In E. negrosensis HNS , 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. procera HNS and E. wittei HNS , penis valve apodemes terminate dorsally (fig. 1B); in lateral view, penis valves project dorsally above parameres; digiti anvil-shaped (weakly anvil-shaped in E. negrosensis HNS ), 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 Euprenolepis HNS 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 Pseudolasius HNS also exhibits palpal segment reduction. With the exception of E. negrosensis HNS , all species appear to have a 3:4 palpal formula. Pseudolasius HNS typically possess 2 or 3 labial palpal segments. Euprenolepis HNS is most likely to be confused with Pseudolasius HNS , however, with the exception of E. negrosensis HNS , Euprenolepis HNS have much larger eyes than Pseudolasius HNS 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 Euprenolepis HNS from close formicine relatives.

E. negrosensis HNS 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, Chapmanella HNS , by Wheeler (1930), but overall its general morphology suggest placement in Euprenolepis HNS . 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 Euprenolepis HNS species), and a 4:4 palpal formula. This species is at present maintained in Euprenolepis HNS , but this result should be confirmed with molecular data once specimens become available for molecular study.

Morphological characters of E. negrosensis HNS 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 Euprenolepis HNS 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 Euprenolepis HNS 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. negrosensis HNS 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. procera HNS , 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. wittei HNS , 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. procera HNS being by far the most commonly encountered Euprenolepis HNS in collections, majors are still relatively uncommon. Based on the relatively minor morphological differences (other than size) observed between E. procera HNS 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 Euprenolepis HNS

Euprenolepis HNS 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 Cladomyrma HNS , another Southeast Asian endemic formincine genus (Agosti, 1991).

Synopsis of Euprenolepis HNS species

E. echinata HNS , sp. nov.

E. maschwitzi HNS , sp. nov.

E. negrosensis HNS (Wheeler, W.M., 1930: 42)

E. procera HNS (Emery, 1900: 699)

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

E. thrix HNS , sp. nov.

E. variegata HNS , sp. nov.

E. wittei HNS , sp. nov.

E. zeta HNS , sp. nov.

FIGURE 2. Distribution of Euprenolepis HNS species.

Names excluded from Euprenolepis HNS

Paratrechina helleri HNS (Viehmeyer, 1914), COMB. NOV

Prenolepis (Euprenolepis) helleri, Viehmeyer HNS , 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 Paratrechina HNS ; Bolton, 1995: 189, combination in Euprenolepis HNS ; Bolton et al., 2006, in Euprenolepis HNS .

Paratrechina steeli HNS (Forel, 1910), COMB. NOV

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

Paratrechina stigmatica HNS , (Mann, 1919), COMB. NOV

Prenolepis (Nylanderia) stigmaticus, Mann HNS , 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 Euprenolepis HNS ; Bolton, 1995: 189, in Euprenolepis HNS ; Bolton et al., 2006, in Euprenolepis HNS .

Key to Euprenolepis HNS workers

(As E. procera HNS 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. procera HNS 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....................................................................................................................... negrosensis HNS

- 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............................................................................................................................................................... procera HNS

- 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 .......................................................................................................................................... thrix HNS

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

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 ......................................................................................................................................................................... echinata HNS

- 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......................... maschwitzi HNS

- 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...... variegata HNS

- 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............................................................................................................................................ wittei HNS

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