Cylindromyrmex brevitarsus

Inhabits a range of forest types: montane wet, mesophil, mature cloud and tropical moist forest. Samples have come mostly from flight traps with a few from litter samples and one from dead wood.

Identification
De Andrade (1998) - A species belonging to the brevitarsus clade and resulting in an unresolved position with Cylindromyrmex darlingtoni and Cylindromyrmex electrinus, but differing from darlingtoni by the frontal carinae reaching the anterior border of the clypeus instead of longer than the clypeus, and by the mandibles with 6-8 denticles instead of 9-10: and from electrinus by the mid and fore basitarsi shorter and broader distally instead of long, with parallel sides, and by the yellow-light brown femora instead of black.

C. brevitarsus is very similar to darlingtoni. Both species can be separated as stated in the diagnosis and, in addition, also by the hind coxae ventrally (1937) gave the following characters to separate brevitarsus from darlingtoni: mandibular shape and dentition, body colour, and size of the eyes. Material available for the present study proves that the body colour and the size of eyes are too variable to be useful to separate brevitarsus from darlingtoni. The gynes of brevitarsus vary remarkably in size (see measurements). The gynes from Corcovado (MZSP) and Jatai (MZSP) are small (TL: 5.88-5.96). Those from Aragua (MIZA), Rio Negro (NHMB), Silva Jardim (MZSP), and Sucumbios (LACM) are intermediate (TL: 7.44-7.64). Those from Nova Friburgo (BMNH) and from Flore ta da Tijuca (MZSP) are the largest (TL: 8.20-9.40). There seem to be no relevant morphological differences between small and intermediate size gynes, only the mandibles are shorter and less convex in the small ones. The large gynes differ from the others by the ventral process of the petiole more round. The large size gynes also have the mandibles convex and massive as in the medium ones. From the material available for the present study I find insufficient evidence to regard them as belonging to two (or three) different species.

A Brazilian male from Butantan which I also consider brevitarsus has larger size 8.96 instead of 5.98-8.04 (see measurements), more impressed sculpture and darker legs. A comparison of its genitalia with those of two males of “normal” size and shows no significant differences.

Some workers and gynes of brevitarsus may also have the second gastric tergite striate.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Costa Rica, Ecuador, Guatemala, Mexico, Peru, Venezuela.

Nomenclature

 *  brevitarsus. Cylindromyrmex brevitarsus Santschi, 1925b: 5 (w.) BRAZIL. De Andrade, 1998a: 625 (q.m.). Combination in C. (Hypocylindromyrmex): Kempf, 1972a: 91. See also: Brown, 1975: 38.

Description
De Andrade (1998):

Worker
TL 4.20-6.44; HL 0.86-1.20; HW 0.75-0.98; SL 0.36-0.43; SW 0.16-0.19; WL l .04-1.50; PeI 0.36-0.56; PeW 0.41-0.58; HFeL 0.49-0.64; HFeW 0.26-0.30; HTiL 0.40-0.54; HTiW 0.16-0.19; HBaL 0.20-0.29; HBaW 0.06-0.08; CI 81.7-89.2; SI 42.5-45.0; HFeI 45.3-46.9; HTiL 35.2-40.5; HBaI 26.9-31.8.

Head ca. 1.6-1.7 times longer than broad, with subparallel sides. Occiput high. Vertexal angles convex. Frontal carinae about half as broad as the maximum head width. Anterior half of the frontal carinae diverging backward and reaching the middle of the eyes posteriorly. Dorsum of the frontal carinae with an impressed, broad, median sulcus anteriorly. Frontal carinae as long as the anterior border of the clypeus. Compound eyes small (minimum 30 and less than 150 ommatidia), flat and on the posterior half of the head. Ocelli reduced to very superficial pits. Scapes reaching the anterior border of the eyes. Proximal third of the scapes ½ narrower than the distal parts. Mandibles convex dorsally. Masticatory margin of the mandible each with a series of 6-8 irregular denticles followed by an apical one.

Mesosoma convex dorsally and slightly longer or shorter than the head (mandibles included). Pronotum with parallel sides. Promesonotal and propodeal sutures less impressed than in darlingtoni. Mesonotum slightly narrower than pronotum. Propodeum with the sides gently convex and converging posteriorly. Basal face of the propodeum eparated from the declivous one by a faint margin.

Petiole quadrate, slightly broader than long, anteriorly truncate and the dorsally convex. Ventral process of the petiole large and triangular. Postpetiole ca. 1.4 broader than long. Postpetiolar sides gently diverging posteriorly. Postpetiole in dorsal view slightly angulate antero-laterally. Postpetiolar sternite antero-medially with traces of a triangular “lip”. Pygidium truncate: its sides bearing many irregularly distributed denticles converging to 4-6 small teeth over the sting.

Legs. Femora and tibiae inflated. Fore and Mid basitarsi strongly broadening distally. Hind basitarsi short, ca. ½ shorter than the maximum length of the hind tibiae. Mid basitarsi about 1/2 shorter than the hind basitarsi. Outer apical edge of the hind and of the mid basitarsi respectively with 4,5 spine-like setae.

Sculpture. Head covered by thin, longitudinal striae, thicker on the posterior third of the head dorsum and absent on the corners of the ventral part of the head. Mesosoma longitudinally striated. Dorsum of the pronotum with about 34-38 longitudinal striae similar to those on the posterior part of the head dorsum. Pronotal striae prolonging to the dorsum of the mesonotum and propodeum. Pleurae with thin, superficial, longitudinal striae, less impressed on the propleurae. Petiolar dorsum with about 31 -35 striae similar to those on the propodeum. Petiolar sides minutely and superficially reticulate. Declivous face of the propodeum and anterior face of the petiole smooth or with similar sculpture as on the petiolar sides. Dorsum of the postpetiole densely covered by striae similar to those on the petiolar dorsum. Center of the first gastric tergite with thin, short, longitudinal striae, thinner than those on the postpetiole, mature specimens have the whole first gatric tergite covered by striae and the second gastric tergite with striae on the center only. Postpetiolar sternites and remaining gastric segments smooth and with sparse punctures. Pygidium, border of the sternites, and legs superficially reticulate. Hind coxae with thin, longitudinal striate. Mid coxae with few, fainter striate than those on the hind coxae.

Pilosity as in Cylindromyrmex darlingtoni.

Colour light or dark brown. Legs yellowish-orange to light brown with darker coxae and basitarsi.

Queen
TL 5.88-9.40; HL 0.95-1.52; HW 0.80-1.28; EL 0.35-0.46; SL 0.37-0.64; SW 0.16-0.24; WL 1.52-2.04; PeI 0.47-0.78; PeW 0.45-0.72; HFeL 0.53-0.93; HFeW 0.25-0.40; HTiL 0.46-0.81; HTiW 0.18-0.27; HBaL 0.28-0.50; HBaW 0.06-0.09; CI 78.5-84.5; SI 37.5-43.2; HFeI 42.5-47.9; HTiL 32.4-39.1; HBaI 17.4-22.6.

Very similar to the worker but differing from it in the following details: compound eyes very large, flat or gently convex and largely on the posterior part of the head: mandibles with 6-8 denticles; ocelli well defined: mesosoma broad medially: parapsidal furrows weakly impressed: petiole slightly longer than broad: scutellum with very thin, superficial striae, sometimes on the anterior half only; propodeal dorsum with striae thinner than those on the pronotum and on the mesonotum. Some gynes have short striae on the second gastric tergite.

Colour dark brown or black. Antennae, mandibles and coxae dark ferrugineous or brown. Some specimens have the anterior half of the head dorsum dark ferrugineous. Legs dark yellowish-orange or light brown with darker coxae and tarsi. The gyne from Ecuador (LACM) and Serra Norte (MPEG) have the femora light brown with yellowish tibiae.

Male
TL 5.98-8.96; HL 0.85-1.18; HW 0.81-1.24. EL 0.44-0.61; SL 0.19-0.28; SW 0.13-0.19; WL 1.80-2.84; PeL 0.48-0.84; PeW 0.43-0.76; HFeL 0.68-1.06, HFeW 0.17-0.23: HTiL 0.59-0.85; HTiW 0.14-0.19; HBaL 0.44-0.69; HBaW 0.05-0.07; CI 89.6-105.1; SI 57.1-73.1; HFeI 22.3-27.9; HTiI 21.0-25.4; HBaI 10.1-13.6.

Head slightly longer than broad. Vertexal angles converging to the subtruncate vertexal margin. Ocelli protuberant. Compound eyes broadly convex and largely on the anterior part of the head. Borders of the frontal carinae broad, convex anteriorly, converging and subparallel posteriorly. Frons anteriorly concave, medially convex and posteriorly sloping towards the impair ocellus. Anterior border of the clypeus medially convex. Mandibles long: their masticatory margin edentated and with a pointed apical tooth. Scapes about 1/4 longer than broad. Funicular joints narrowing from the base to the apex.

Mesosoma robust. Pronotum in dorsal with the sides diverging posteriorly. Mesonotum slightly convex. Mayrian carinae absent. Parapsidal furrows superficially impressed. Basal face of the propodeum narrowing backwards and separated from the declivous one by a marked carina.

Petiole slightly longer than broad; anteriorly truncate and dorsally convex. Petiolar sides broadening backwards. Ventral process of the petiole subtriangular. Postpetiole broadening backwards and narrower than the first gastric tergite. Postpetiole antero-laterally subround.

First gastric segment broader than the postpetiole. Second gastric segment narrower or as broad as the first segment. Remaining gastric segments narrowing backwards.

Legs. Femora not inflate. Mid and hind basitarsi long.

Sculpture. Head dorsum minutely punctate and with thin striae, the punctures more impressed on the anterior half, the striae slightly longitudinal between the ocelli, and on the frons, diverging from the eyes to the frontal carinae. Vertex and sides of the ventral part of the head smooth and with variably distributed small piligerous foveae. Middle of the ventral part of the head with short, transversal striae. Pronotum smooth and with sparse piligerous foveae on the center; some specimens with additional irregular, transversal striae between the foveae. Mesonotum and scutellum smooth and with rare. small foveae. Basal face of the propodeum and petiole covered by thick, irregular, longitudinal striae, sometimes missing on the center of the petiole. Declivous face of the propodeum punctate and with rare, very thin, transversal rugosities close to the border. Pro- and mesopleurae smooth. Metapleurae striated as on the basal face of the propodeum, the striae thicker and less regular ventrally. Postpetiole, first gastric segment and legs smooth and with superficial punctures, denser and deeper on the three last gastric segments.

Pilosity. Body covered by pointed hair of three types: (1) long, sparse and suberect, denser on the last three gastric segments: (2) shorter than the type (1) and variably distributed on the body: (3) mixed and shorter than the type (2), dense on the vertexal angles, on the posterior half of the ventral part of the head, on the coxae and on the gaster.

Colour. Black and shining. Some specimens with the anterior third of the head dorsum, mandibles and antennae orange-ferrugineous or brown. Legs orange-light brown with darker coxae and basitarsi.

Type Material
Worker. Brazil. Type material: 1 worker labelled: “Bresil, Rio Negro, Reichensperger”, in, examined.

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * De Andrade M. L. 2001. A remarkable Dominican amber species of Cylindromyrmex with Brazilian affinities and additions to the generic revision (Hymenoptera: Formicidae). Beiträge zur Entomologie 51: 51-63.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/
 * Longino, J.T. 2010. Personal Communication. Longino Collection Database