Cylindromyrmex whymperi

A wide ranging forest species that is also found on the Galapagos Islands.

Identification
De Andrade (1998) - A Cylindromyrmex species belonging to the striatus clade, resulting as sister species of Cylindromyrmex striatus, but differing from it in the worker and gyne by the thicker body striation, and by the posterior third of the head dorsum with 25 longitudinal striae at most instead of more than 34.

The species whymperi and striatus are very similar to each other in both worker and gyne. Examination of the sculpture shows that the striae of whymperi are much thicker than those of striatus, especially on the head dorsum and postpetiole. The head of whymperi is shorter and with more convex sides than the one of striatus. There seems to be little variation in the thickness of the striae on the mesosoma and on the postpetiole of workers and whymperi. The specimens from Hac de Tenguel are those with the thickest mesosomal and postpetiolar striation. Two workers, one from Bolivia (NHMB) and the other from Costa Rica (IAVH) have thinner striation on the postpetiole but still definitely thicker than that of striatus. Normally gynes of whymperi have thicker and less striae on the postpetiole than the gynes of striatus. Ten out of eleven gynes of whymperi have 22-24 striae on the postpetiole. Only a gyne from Costa Rica (LACM) has 30 striae on the postpetiole, approaching in this way the gynes of striatus with 30-34. C. whymperi exhibits also some colour variation. Rare workers and gynes have the distal half of the tibiae dark brown. The subspecies striatus tibialis Stitz is based on specimens with a similar type of coloration.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, Galapagos Islands, Guatemala, Mexico, Peru.

Biology
De Andrade (1998) - There are no elements to assert whether whymperi is introduce or indigenous in the Galapagos Islands. The most remarkable fact about its distribution is that, judging from the collection records, it seems to be common on the islands. Its success there, however, can be explained in both ways, i.e. by being native of the islands or by the lack of competition after its introduction. Wheeler (1919) mentioned “striatus” from a house of Indefatigable Island (Galapago. Is.). Wheeler (1924, 1936) reports “williamsi” nesting in dead branches of the Celastraceous shrub Mayretenus obavata whose dead parts contained flourishing colonies of Calotermes pacificus. The specimens collected on the Ferdinanda Is. By R. Silberglied were under the bark of Bursera graveolens (Burseraceae).

Jack Longino: At La Selva I collected fragments of dead workers from a dead Piper stem, in mature forest understory.

Dr. Bruno Gobin sent me specimens to identify. The material he sent included workers and a dealate queen. He stated "We collected them from a forager raid of about 100 workers in Rincon de la Vieja (along the Volcano trail, not far beyond the suspension bridge). Unfortunately, we could not see what they were raiding, but in the lab they readily recruited to some termites." These results were later published (Goben et al. 2001), along with a description of a novel exocrine gland.

Goben et al. (2001): Workers of the ant Cylindromyrmex whymperi display mass trail recruitment. Bioassays show that the trail pheromone originates from a unique gland between abdominal sternites 6 and 7. The gland has a hitherto unknown structural organization. Upon leaving the secretory cell, the duct cell widens to form a sclerotized pear-shaped reservoir chamber, lined with multiple duct cells. Each duct thus forms a miniature reservoir for the secretions of each single secretory cell, a novel structural arrangement in exocrine glands of social Hymenoptera.

Nomenclature

 *  whymperi. Holcoponera whymperi Cameron, 1891: 92, fig. (w.) ECUADOR. Combination in Cylindromyrmex: Forel, 1892f: 256. Junior synonym of striatus: Emery, 1901a: 54. Revived from synonymy and senior synonym of schmidti, tibialis, williamsi: De Andrade, 1998a: 596.
 * williamsi. Cylindromyrmex williamsi Wheeler, W.M. 1924a: 101, fig. 19 (w.q.) ECUADOR (Galapagos Is). Junior synonym of striatus: Brown, 1975: 38; of whymperi: De Andrade, 1998a: 596.
 * schmidti. Cylindromyrmex (Metacylindromyrmex) schmidti Menozzi, 1931d: 191, figs. 3, 4 (w.q.) COSTA RICA. Junior synonym of whymperi: De Andrade, 1998a: 597. See also: Brown, 1975: 38.
 * tibialis. Cylindromyrmex (Hypocylindromyrmex) striatus var. tibialis Stitz, 1932a: 367 (q.) ECUADOR (Galapagos Is). Junior synonym of striatus: Brown, 1975: 38; of whymperi: De Andrade, 1998a: 596.

Description
De Andrade (1998):

Worker
TL 5.02-7.40; HL 1.08-1.56; HW 0.90-1.28; EL 0.31-0.45; SL 0.44-0.68; SW 0.15-0.19; WL l.12-1.88; PeL 0.44-0.76; PeW 0.48-0.80; HFeL 0.61-0.93; HFeW 0.22-0.30; HTiL 0.60-0.97; HTiW 0.16-0.23; HMeL 0.46-0.76; HMeW 0.07-0.10; CI 78.9-83.3; SI 27.9-34.1; HFeI 32.4-36.1; HTiI 23.7-26.2; HBaI13.0-15.2.

Head about 1/6 longer than broad, with slightly convex sides. Occiput low. Vertexal angles round. Frontal carinae about half broad as the maximum head width. Sides of the frontal carinae diverging posteriorly or gently convex medially. Dorsum of the frontal carinae with an impressed, short, median sulcus anteriorly. Frontal carinae not reaching the anterior border of the clypeus. Compound eyes large, convex and slightly behind the mid line of the head. Ocelli developed. Scapes surpassing the anterior border of the eyes. Proximal fifth of the scape 1/2 narrower than the remaining parts. Mandibles flat dorsally and shorter than in Cylindromyrmex brasiliensis. Mandibles laterally angulate at the base. Masticatory margin of the mandibles with a set of 4-5 irregular denticles followed by an apical tooth. Hypostomal bridge narrow, with the antero-lateral margin concave.

Mesosoma gently convex dorsally and as long as or slightly longer than the head (mandibles included). Pronotum with parallel sides. Mesonotum narrower than pronotum. Propodeal sides converging posteriorly. Basal face of the propodeum separated from the declivous one by a marked margin converging medially.

Petiole sub-quadrate, with the sides gently diverging backwards. Anterior face of the petiole truncate and the dorsal one convex. Ventral process of the petiole triangular and slightly smaller than in brasiliensis. Postpetiole broader than long and with convex sides. Postpetiolar sternite antero-medially with a variably marked triangular “lip.” Postpetiole in dorsal view antero-laterally angulate. Pygidium in side view obliquely truncate. Pygidium in dorsal view with the sides bearing a row of denticles strongly converging to a pair of small teeth over the sting.

Legs. Femora and tibiae not inflated. Hind metatarsi long and about 1/5 shorter than the maximum length of the hind tibiae. Outer apical edge of the hand and of the mid basitarsi with 6 or 7 spine-like setae.

Sculpture. Posterior third of the head dorsum and frontal carinae with thick, longitudinal striae, thinner on the anterior half of the frontal carinae. Rare, small, piligerous foveae can be present behind the ocelli. Anterior half of the head dorsum with striae converging towards the scrobes, these striae thinner than those on the anterior half of the frontal carinae. Ventral part of the head with longitudinal striae laterally, smooth and superficially punctate medially. Mesosoma with 11-15 longitudinal striae similar or slightly thicker than those on the posterior third or the head dorsum. Lower pro- and metapleurae, and mesopleurae with thin longitudinal striae similar to those on the anterolateral part of the head dorsum. Upper pro- and metapleurae with striae as on the anterior part of the frontal carinae. Petiolar dorsum with 9-14 striae similar to those on the mesosoma. Petiolar sides minutely reticulate and with less regular and thinner striae than those on its dorsum. Declivous face of the propodeum and anterior face of the petiole minutely and superficially reticulate. Dorsum of the postpetiole with ca. 19-25 striae as thick as or slightly thinner than those on the mesosoma. Postpetiolar sternite smooth or reticulate and with sparse piligerous foveae. First, second, and third gastric tergites and first gastric sternites smooth and with sparse punctuations. Remaining gastric segments reticulate-punctate. Hind coxae with few, faint, longitudinal striae. Legs with very superficial, minute punctures.

Pilosity similar to brasiliensis.

Colour black and shining. Tibiae of three pairs of legs yellowish with the distal borders brown. Tarsomeres brown.

Queen
TL 7.58-8.16; HL 1.44-1.46; HW 1.16-1.20; EL 0.45-0.46; SL 0.56-0.60; SW 0.16-0.18; WL 2.36-2.40; PeL 0.73-0.76; PeW 0.69-0.72; HFeL 0.82: HFeW 0.30-0.31: HTiL 0.75-0.78; HTiW 0.23-0.24; HBaL 0.64-0.66; HBaW 0.09-0.11; CI 80.5-82.2; SI 29.2-34.1; HFeI 36.6-37.8; HTiI 23.9-26.7; HBaI 13.3-15.5.

Similar to the worker, from which it differs by the following peculiarities: vertex less concave medially; mesosoma broad medially; parapsidal furrows impressed; petiole slightly longer than broad; pronotum with 14-17 thick, longitudinal striae, mesonotum medially with 9-10 longitudinal striae, slightly thinner than those on the pronotum, those on the sides less regular and shorter than the median ones; scutellum with 7-8 striae as those on the pronotum; dorsum of the propodeum with 14 striae as those on the pronotum; petiolar dorsum with 9-10 longitudinal striae as those on the pronotum: postpetiolar dorsum with 22-30 longitudinal striae slightly thinner than those on the pronotum.

Male
TL 7.58-8.14; HL 1.04-1.12; HW 1.02-1.14; SL 0.24-0.28; SW 0.15-0.16; WL 2.40-2.72; PeL 0.68-0.80; PeW 0.67; HFeL 0.91-0.98; HFeW 0.18-0.20; HTiL 0.79-0.87; HTiW 0.17-0.18; HBaL 0.62-0.71; HBaW 0.07-0.08; CI 96.3-101.8; SI 57.1-62.5; HFeI 19.8-21.3; HTiI 20.6-21.5; HBaI 11.3.

Head as broad as long. Vertexal margin subtruncate or convex. Ocelli protuberant. Compound eyes broadly convex and largely on the anterior part of the head. Borders of the frontal carinae raised and diverging backwards. Frons anteriorly slightly concave, medially convex and posteriorly sloping toward the impair ocellus. Clypeus declivous; its anterior border straight. Mandibles long with edentated masticatory margin and with a pointed apical tooth. Scapes thick and shorter than first and second funicular joints. Funicular joints as in Cylindromyrmex brasiliensis.

Mesosoma robust. Pronotum in dorsal view with subparallel sides. Mesonotum convex. Pair Mayrian carinae superficially impressed. Parapsidal furrow impressed. Scutellum slightly higher than the mesonotum. Basal face of the propodeum narrowing backwards and separated from the declivous one by a developed and well marked carina. Middle of the basal face of the propodeum sometimes with a longitudinal sulcus.

Petiole sub-quadrate. Anterior face of the petiole truncate and separated from the dorsal one by a marked carina. Ventral process of the petiole subtriangular. Postpetiole broadening backwards and narrower than the first gastric tergite.

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

Sculpture. Head dorsum with striae converging from the posterior half of the compound eyes to the ocelli. Striae behind the ocelli slightly transversal. Striae between half of the frontal carinac with traces of longitudinal striae. Anterior half of the frontal carinae with striae converging posteriorly. Head dorsum behind the clypeus with striae diverging to the compound eyes. Area close to the insertion of the scape sometimes smooth or with few traces of irregular striae. Ventral part of the head minutely punctate and with sparse, superficial piligerous foveae and thin striae: the striae slightly longitudinal on the middle of the head and perpendicular close to the eyes. Dorsum of the pronotum with irregular, transversal striae and few irregular foveae. Mesonotum and mesopleurae smooth, with sparse piligerous punctures. Scutellum with variably impressed longitudinal striae. Basal face of the propodeum and metapleurae covered by thick longitudinal striae. Declivous face of the propodeum smooth. Propleurae with longitudinal striae as those on the scutellum. Petiole with longitudinal striae and few foveae, the striae sometimes very superficial or absent on the dorsum and marked on the side. Postpetiole, first gastric segment and legs smooth and with sparse, superficial punctures. Remaining gastric segments superficially punctate.

Pilosity. Body covered by pointed hairs of three types: (1) long, suberect, dense on the last gastric segments; (2) shorter and denser than the type (1); (3) shorter than the type (2). decumbent, dense on the coxae, on the anterior face of the fore and mid femora and on the ventral face of the tibiae.

Colour. Black and shining. Anterior third of the head dorsum, mandibles, funiculi and tibiae yellowish-orange to light brown, scapes, coxae, femora and tarsi darker.

Type Material
Ecuador. Holotype worker "Whymp. Supp. App. p. 92 Holcoponera whympheri Cam. type." examined.

Examination of the material labelled as “typus” of schmidti by Menozzi shows several contradictory points. The type locality of schmidti is La Caja (Costa Rica) and the “type” (worker?) should have been deposited in the Deutsches Entomologiches Museum and a “cotype” in his own collection. Two workers labelled “S. Jose, Costa Rica, Holotypus, Paratypus. Cylindromyrmex schmidti. Typus! Menoz., Menozzi deter.” are preserved in the Deutsches Entomologiches Institut of Eberswalde. These workers are identical to whymperi. They are unlikely to be the holotype and paratype of schmidti because the locality name does not correspond to the one given by Menozzi (1931). Two workers and a gyne of schmidti labelled “La Caja: 8 kil. w. San Jose C. R., Heinr. Schmidt. TYPUS,” are preserved in the Menozzi collection. These workers are similar to whymperi and are likely to be the true syntype of schmidti. The gyne does not fit the description and drawing of the gyne of schmidti by Menozzi (1931). Additional material in the IEGG contains two other gynes with labels similar to those of the “syntype” workers of schmidti and fit exactly the description of Menozzi (1931). These two gynes correspond to meinerti Forel.

References based on Global Ant Biodiversity Informatics

 * Bezdeckova K., P. Bedecka, and I. Machar. 2015. A checklist of the ants (Hymenoptera: Formicidae) of Peru. Zootaxa 4020 (1): 101–133.
 * Branstetter M. G. and L. Sáenz. 2012. Las hormigas (Hymenoptera: Formicidae) de Guatemala. Pp. 221-268 in: Cano E. B. and J. C. Schuster. (eds.) 2012. Biodiversidad de Guatemala. Volumen 2. Guatemala: Universidad del Valle de Guatemala, iv + 328 pp
 * Brown W. L., Jr. 1975. Contributions toward a reclassification of the Formicidae. V. Ponerinae, tribes Platythyreini, Cerapachyini, Cylindromyrmecini, Acanthostichini, and Aenictogitini. Search Agric. (Ithaca N. Y.) 5(1): 1-115.
 * 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).
 * Menozzi C. 1931. Qualche nuova formica di Costa Rica (Hym.). Stettiner Entomologische Zeitung. 92: 188-202.