Eutetramorium parvum

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Eutetramorium parvum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Eutetramorium
Species: E. parvum
Binomial name
Eutetramorium parvum
Bolton & Fisher, 2014

Eutetramorium parvum casent0102296 p 1 high.jpg

Eutetramorium parvum casent0102296 d 1 high.jpg

Specimen Labels

Known only from the types that were collected from a soil/litter sample in humid forest.

Identification

Known only from the type-series, parvum is easily distinguished from the two previously known species as it is very small by comparison, is yellow, has a reduced palp formula, is more finely sculptured, lacks mesotibial and metatibial spurs, and despite its small size has eyes that are relatively larger than in its congeners. (Bolton and Fisher 2014)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.
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Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.
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Biology

Castes

Males have yet to be collected.

Worker

Images from AntWeb

Eutetramorium parvum casent0102297 h 1 high.jpgEutetramorium parvum casent0102297 p 1 high.jpgEutetramorium parvum casent0102297 d 1 high.jpgEutetramorium parvum casent0102297 l 1 high.jpg
Worker. Specimen code casent0102297. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by NHMUK, London, UK.
Eutetramorium parvum casent0195002 h 1 high.jpgEutetramorium parvum casent0195002 p 1 high.jpgEutetramorium parvum casent0195002 d 1 high.jpgEutetramorium parvum casent0195002 l 1 high.jpg
Holotype of Eutetramorium parvumWorker. Specimen code casent0195002. Photographer Michele Esposito, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.
Eutetramorium parvum casent0173546 h 1 high.jpgEutetramorium parvum casent0173546 p 1 high.jpgEutetramorium parvum casent0173546 d 1 high.jpgEutetramorium parvum casent0173546 d 2 high.jpgEutetramorium parvum casent0173546 l 1 high.jpg
Paratype of Eutetramorium parvumWorker. Specimen code casent0173546. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.

Queen

Images from AntWeb

Eutetramorium parvum casent0102298 h 1 high.jpgEutetramorium parvum casent0102298 p 1 high.jpgEutetramorium parvum casent0102298 d 1 high.jpgEutetramorium parvum casent0102298 l 1 high.jpg
Queen (alate/dealate). Specimen code casent0102298. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by NHMUK, London, UK.
Eutetramorium parvum casent0173545 h 1 high.jpgEutetramorium parvum casent0173545 p 1 high.jpgEutetramorium parvum casent0173545 d 1 high.jpgEutetramorium parvum casent0173545 l 1 high.jpg
Paratype of Eutetramorium parvumQueen (alate/dealate). Specimen code casent0173545. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.

Nomenclature

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

  • parvum. Eutetramorium parvum Bolton & Fisher, 2014: 14, figs. 7-9, Map 125 (w.q.eq.) MADAGASCAR.

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

Description

Worker

(holotype in parentheses). TL 2.7 (2.7), HL 0.64–0.66 (0.64), HW 0.56–0.59 (0.59), CI 88–92 (92), SL 0.44–0.48 (0.46), SI 78–81 (78), PW 0.38–0.42 (0.40), WL 0.70–0.73 (0.72) (4 measured).

Palp formula 4,2. Cephalic dorsum extremely finely, densely, longitudinally costulate, the costulae diverging and becoming weaker posteriorly; spaces between costulae finely punctulate. Eyes slightly in front of midlength of head in full-face view, EL 0.14–0.15 (EL/HW 0.24–0.25). Sides of head without projecting setae except for a single short seta at the posterior corner. Dorsum of head with a few short, standing setae, and sparse decumbent pubescence. Mesotibia and metatibia without spurs (or spurs so reduced that they cannot be distinguished from apical setae by light microscopy). Metafemur short, MfL 0.52–0.54 (MfL/HW 0.90–0.93). Mesosoma in profile with metanotal groove impressed, the outline of the propodeum just behind the groove rising to a peak, then sloping posteriorly to the spines. Promesonotal dorsum with sparse, short setae. Propodeal dorsum with setae on the crest immediately behind the metanotal groove, but otherwise absent. Pronotal dorsum very finely reticulate-rugulose, the spaces between the rugulae densely punctulate. Petiole in profile with an angulate anteroventral process that is followed by a cuticular crest which extends back to the level of the spiracle; the latter located just anterior to the ascending face of the node. In dorsal view nodes of both petiole and postpetiole broader than long, the postpetiole with length ca 0.20, width ca 0.26. Setae on dorsum of first gastral tergite numerous, short and subdecumbent. First gastral tergite unsculptured except for small pits from which the setae arise. Full adult colour dull yellow to light brownish yellow.

Queen

(gyne). Presumed alate when virgin, the single specimen known is dealate. TL 3.6, HL 0.75, HW 0.71, CI 95, SL 0.52, SI 73, PW 0.56, WL 1.00, MfL 0.64 (MfL/HW 0.90), EL 0.22 (EL/HW 0.31) (1 measured). Postpetiole dorsal length 0.28, width 0.34. As worker but larger, with conspicuous ocelli and a full complement of flight sclerites. First gastral tergite much broader than in worker (0.87 as opposed to worker ca 0.56). Mesoscutum and scutellum longitudinally costulate.

Ergatoid? A single specimen in the type-series basically resembles a worker, but is decidedly larger, TL 3.0, HL 0.71, HW 0.64, CI 90, SL 0.49, SI 77, PW 0.46, WL 0.82, MfL 0.60 (MfL/HW 0.94), EL 0.16 (EL/HW 0.25). Postpetiole dorsal length 0.24, width 0.28. Otherwise the same as the paratype workers; without flight sclerites but mesonotum more prominent and better defined than in the genuine workers. Maximum width of first gastral tergite 0.64 (ca 0.56 in worker and 0.87 in queen).

As so few specimens are known it is not possible to tell if this individual represents a larger caste of worker, a worker-queen intercaste, or an ergatoid form. Fresh material will be needed, so that this form can be dissected to assess the condition of the ovaries and establish whether spermathecae are present.

Type Material

Holotype worker (top specimen of 3 on pin), Madagascar: Prov. Toliara, Chaines Anosyennes, Massif Nord, zone summitale, 1900 m., 20.ii.1971, JMB 2048, 2048.8674w, CASENT0195002 (Peyrieras) (California Academy of Sciences). Paratypes. 4 workers (2 on same pin as holotype), 1 possible ergatoid, 1 dealate queen (gyne); with same data as holotype but the pin bearing the dealate queen with a label, “lavage de sol et litiere. Foret dense humide de montagne” (CASC). [A number of specimens from the same series, in The Natural History Museum, are also to be regarded as paratypes.]

References

  • Bolton, B. & Fisher, B.L. 2014. The Madagascan endemic myrmicine ants related to Eutetramorium (Hymenoptera: Formicidae): taxonomy of the genera Eutetramorium Emery, Malagidris nom. n., Myrmisaraka gen. n., Royidris gen. n., and Vitsika gen. n. Zootaxa 3791, 1–99.

References based on Global Ant Biodiversity Informatics

  • Bolton B., and B. L. Fisher. 2014. The Madagascan endemic myrmicine ants related to Eutetramorium (Hymenoptera: Formicidae): taxonomy of the genera Eutetramorium Emery, Malagidris nom. n., Myrmisaraka gen. n., Royidris gen. n., and Vitsika gen. n. Zootaxa 3791(1): 1-99.