Strumigenys signeae

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Strumigenys signeae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. signeae
Binomial name
Strumigenys signeae
Forel, 1905

Strumigenys signeae casent0217957 p 1 high.jpg

Strumigenys signeae casent0217957 d 1 high.jpg

Specimen Labels

Known from litter samples collected in rainforest and wet forest.

Identification

Bolton (2000) - A member of the signeae complex in the Strumigenys godeffroyi-group. Of the species grouped here with signeae (see under signeae-complex), Strumigenys ahares is immediately isolated by its peculiarly shaped mandibles. In full-face view they have concave outer and convex inner margins, the latter touching at full closure through the basal part of their length and separating and diverging distally; this specialisation is unique in the group.

The closely related species signeae and Strumigenys valefor both have a conspicuous series of freely laterally projecting stout hairs on the dorsolateral margin of the head. The first hair in the series is located anterior to the level of the apex of the scrobe and the remainder form a sequence that diminishes in length to the occipital corner. The presence of a broad cuticular lamella on the inner mandibular margin is diagnostic of signeae. This feature is by no means unique in the regional fauna but the structure as described above, coupled with the pilosity characters noted, will isolate signeae from all other species in the group. Under light microscopy the mandibular lamella appears thin and translucent but with electron microscopy it appears opaque and solid. This is because light can penetrate the thin cuticular sheet but an electron beam is completely reflected by it. S. valefor lacks the mandibular lamella but does have a very narrow cuticular rim or carina for part of the length of the inner mandibular margin; this is extremely slender and inconspicuous by comparison with signeae. The head of valefor is rather more slender than than that of signeae and its scapes tend to be longer: valefor CI 67-71, SI 83-88; signeae CI 73-78, SI 72-79.

The remaining four species grouped here (Strumigenys izepara, Strumigenys sublaminata, Strumigenys uichancoi, Strumigenys virgila) do not have a row of coarse marginal hairs on the head, nor do they show any striking oddities in mandibular morphology like those mentioned above. However, virgila has a characteristic apical mandibular dentition that consists of an intercalary tooth with two denticles between it and the apicoventral tooth; usually there is also a denticle between the intercalary tooth and the apicodorsal spiniform fork tooth. S. virgila also has a large lateral spongiform lobe on the petiole (small in the others). The dorsal margin of this lobe is very high on the side and extends the length of the node, as is usual in the godeffroyi-complex but is otherwise unknown in the species here grouped with signeae.

Of the final three species izepara and sublaminata have relatively short scapes, SI 62-69. S. sublaminata has shorter mandibles (MI 35-39) than izepara (MI 47). S. izepara also has short standing hairs present at the highest point of the vertex (absent from sublaminata), has the pronotal dorsum mostly smooth (densely reticulate-punctate in sublaminata), and has the hairs on the first gastral tergite slender and simple (stout and weakly remiform in sublaminata).

The final species, uichancoi has longer scapes than the two just discussed, SI 85. S. uichancoi has the pronotal dorsum smooth and has a broad lamella on the propodeal declivity. It also lacks a freely laterally projecting apicoscrobal hair. Instead the entire dorsolateral margin, from the frontal lobe to the occipital corner, has a dense row of small slender anteriorly curved hairs that are all about the same size and shape.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Brunei Darussalam, Indonesia (type locality), Malaysia, Philippines, Singapore.
Oriental Region: Thailand.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • signeae. Strumigenys signeae Forel, 1905c: 10 (w.) INDONESIA (Java). See also: Bolton, 2000: 826.

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

Description

Worker

Bolton (2000) - TL 2.5-2.9, HL 0.65-0.80, HW 0.47-0.60, CI 73-78, ML 0.30-0.38, MI 46-50, SL 0.36-0.44, SI 72-79, PW 0.27-0.32, AL 0.66-0.77 (20 measured).

Characters of signeae-complex. With head in full-face view outer margin of mandible more or less straight. Inner margin of mandible with a broad translucent cuticular lamella that extends from base nearly to the preapical tooth; lamella broadens slightly from base toward apex and is broadest just before its termination, where it is about one-third the width of the mandible. In most poplilations the lamella is abruptly truncated at its apex, just proximal of the preapical tooth, but in some it is more rounded and tapered toward its apex. Dorsolateral margin of head with a freely laterally projecting stout remiform hair just anterior to level of apex of scrobe and another in apicoscrobal position; margin posterior to this with 2-3 similar but shorter projecting hairs. Cephalic dorsum with a transverse row of 4-6 erect hairs at occipital margin; without standing hairs anterior to this. Pronotal humeral hair remiform, pronotal dorsum otherwise without erect hairs. Mesonotum with at least a single pair of erect remiform hairs anteriorly; usually also with 1-2 other, much shorter, erect pairs posteriorly. Dorsal alitrunk sometimes entirely densely punctate to reticulate-punctate but this sculpture usually weaker and more diffuse on pronotal dorsum where it is frequently partially to mostly effaced. Side of alitrunk with pleurae and propodeum mostly to entirely smooth. Petiole node in dorsal view broader than long, reticulate-punctate. In profile lateral spongiform lobe of petiole small, confined to posterolateral portion of node. Disc of postpetiole usually more or less smooth medially and with weak punctulate sculpture peripherally, less commonly entire disc smooth; in some even the centre of the disc with superficial sculpture. First gastral tergite with elongate stout weakly remiform hairs.

A small pale worker from Bogor, Java, measures only TL 2.1, HL 0.56, HW 0.41, CI 73, ML 0.27, MI 48, SL 0.32, SI 78, PW 0.24, AL 0.53. This is probably a first-brood worker from an incipient colony.

Type Material

Bolton (2000) - Syntype workers, INDONESIA: Java, Bogor ( = Buitenzorg), 1904 (K. Kraepelin) (Musee d'Histoire Naturelle Genève) [examined].

References

  • Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 826, figs. 435, 500 redescription of worker)
  • Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 321, catalogue)
  • Forel, A. 1905f. Ameisen aus Java. Gesammelt von Prof. Karl Kraepelin 1904. Mitt. Naturhist. Mus. Hambg. 22: 1-26 (page 10, worker described)