Linepithema cryptobioticum

The few collections of this species are all from sifted leaf litter at a single site in the Paraguayan dry chaco. Little is known about the biology of L. cryptobioticum. This species is probably subterranean, as small eyes, robust build, and yellow color are traits typical of hypogaeic ants. (Wild 2007)

Identification
Wild (2007) – Worker Antennal scapes very short (SI 76–81); eyes small, with < 25 ommatidia; frontal carinae relatively widely spaced (CDI > 30); propodeum and petiolar scale unusually tall; mesopleura and metapleural bulla lacking pubescence and strongly shining.

Linepithema cryptobioticum is a distinct ant unlikely to be confused with other species. Linepithema flavescens, known only from Haiti, has slightly larger eyes (>25 ommatidia), a relatively narrow frontal carinal distance (CDI < 30), and lacks the enlarged petiolar scale. Linepithema pulex and Linepithema angulatum are similar in color and in robust build, but these species have larger eyes (>30 ommatidia), longer antennal scapes, and lack the enlarged petiolar scale.

Distribution
Known only from type locality in the Paraguayan chaco.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Paraguay.

Nomenclature

 *  cryptobioticum. Linepithema cryptobioticum Wild, 2007a: 41, figs. 9, 10, 100 (w.) PARAGUAY.

Worker
Holotype: HL 0.58, HW 0.54, MFC 0.17, SL 0.41, FL 0.41, LHT 0.43, PW 0.36, ES 0.78, SI 76, CI 93, CDI 31, OI 13.

Worker: (n = 6) HL 0.56–0.58, HW 0.52–0.54, MFC 0.16–0.18, SL 0.40–0.42, FL 0.39–0.41, LHT 0.40–0.43, PW 0.35–0.36, ES 0.62–0.80, SI 76–81, CI 91–96, CDI 31–33, OI 11–14.

Head in full face view relatively broad (CI 91–96), lateral margins convex, posterior margin concave. Compound eyes small (ES < 0.8), comprised of 17–22 ommatidia. Antennal scapes short (SI 76–81), much shorter than head length. In full face view, scapes in repose not exceeding posterior margin of head. Frontal carinae relatively widely spaced (CDI 31–33). Maxillary palps short, less than ½ HL, ultimate segment (segment six) shorter than segment 2.

Mesosoma in lateral view with pronotum and mesonotum forming a single continuous convexity, mesonotum relatively angulate, without central saddle or indentation. Metanotal groove slightly impressed, propodeum high and relatively bulky, nearly reaching level of mesonotum. Dorsal face with a slight medial saddle-like impression, posterior margin convex dorsad of metapleural bulla.

Petiolar scale unusually tall, in lateral view reaching level of propodeal spiracle. Anterior and posterior faces of scale parallel.

Cephalic dorsum (excluding clypeus) lacking erect setae. Pronotum with 2–3 erect setae (mean = 2.2). Mesonotum usually without erect setae. Erect setae on gastric tergites 1–4 ( = abdominal tergites 3–6) relatively abundant, tergite 1 bearing approximately 10 erect setae of varying length. Venter of metasoma with scattered erect setae.

Sculpture on head and mesosomal dorsum lightly shagreened and moderately shining. Pubescence dense on head, mesosomal dorsum, anterior petiolar scale, and gastric tergites 1–4. Mesopleura and metapleural bulla without pubescence and strongly shining.

Color pale yellow to reddish yellow.

Type Material
Holotype worker. Paraguay. Boquerón: Enciso, 21º12’S 61º40’W, 3-6.xi.2001, M. Leponce & T. Delsinne # 4022-5/3, Dry chaco in sifted litter 1 worker,.

Paratypes. PARAGUAY. Boquerón: Enciso, 21º12’S 61º40’W, M. Leponce & T. Delsinne #4022-5/3, #7597, #22836, Dry chaco in sifted litter, 7 workers,, , , , , ,.

Etymology
The name cryptobioticum refers to the inferred subterranean habits of this species.

References based on Global Ant Biodiversity Informatics

 * Wild, A. L.. "A catalogue of the ants of Paraguay (Hymenoptera: Formicidae)." Zootaxa 1622 (2007): 1-55.