Stenamma leptospinum

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Stenamma leptospinum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Stenammini
Genus: Stenamma
Species: S. leptospinum
Binomial name
Stenamma leptospinum
Branstetter, 2013

Stenamma leptospinum casent0604354 p 1 high.jpg

Stenamma leptospinum casent0604354 d 1 high.jpg

Specimen Labels

Stenamma leptospinum is known only from Winkler and Berlese samples of sifted leaf litter taken from the forest floor. It has been collected from 1650–2000 m elevation in montane wet forest habitats, including cloud forest and montane oak forest.

Identification

Branstetter (2013) - Integument mostly dark brown to brown; medium-sized species (see HL, HW, ML below); lateral margin of hypostomal bridge with a projecting subquadrate to broadly-rounded lobe (usually visible behind mandible in profile); propodeal spines long and rather slender (PSL 00.17–0.22, PSI 1.9–2.2); anterior clypeal margin with a median emargination; basal margin of mandible straight, without a basal notch or depression; head and mesosoma densely carinulate; eye large (EL 0.13–0.15, REL 16–19), with 6–8 ommatidia at greatest diameter; petiolar node in profile subconical, with apex well-defined, almost sharp; postpetiolar node anteroposteriorly compressed; gastral pilosity with a layer of long suberect setae and a sparse layer of shorter decumbent setae; frontal lobes of moderate width (FLD 0.21–0.23, FLI 26–31), not completely obscuring torular lobes in full-face view.

This species could be confused with Stenamma longinoi, Stenamma manni, or Stenamma muralla, but it should be easy to distinguish by its dense carinulate sculpture and long, slender propodeal spines. It is worth noting that the lateral hypostomal lobe that groups S. leptospinum with the other similar species is sometimes reduced, usually becoming shorter and only broadly rounded. When the lobe is reduced it can be more difficult to see in profile view, but it should still be visible from a lateroventral view. I have not seen any specimens where it is completely reduced to a point, as in most other species of Stenamma.

Keys including this Species

Distribution

Southern Mexico. Known only from a few localities in the Sierra Juarez Mountains in Oaxaca Mexico.

Latitudinal Distribution Pattern

Latitudinal Range: 19.51666667° to 17.5278°.

 
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

Distribution based on Regional Taxon Lists

Neotropical Region: Mexico (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

Known only from the worker caste.

Worker

Images from AntWeb

Stenamma leptospinum casent0605530 h 1 high.jpgStenamma leptospinum casent0605530 p 1 high.jpgStenamma leptospinum casent0605530 d 1 high.jpgStenamma leptospinum casent0605530 p 2 high.jpgStenamma leptospinum casent0605530 h 2 high.jpgStenamma leptospinum casent0605530 p 3 high.jpgStenamma leptospinum casent0605530 l 1 high.jpg
Holotype Stenamma leptospinumWorker. Specimen code casent0605530. Photographer Michael Branstetter, uploaded by Default Group. Owned by USNM.
Stenamma leptospinum casent0605531 h 1 high.jpgStenamma leptospinum casent0605531 p 1 high.jpgStenamma leptospinum casent0605531 d 1 high.jpgStenamma leptospinum casent0605531 p 2 high.jpgStenamma leptospinum casent0605531 l 1 high.jpg
Paratype of Stenamma leptospinumWorker. Specimen code casent0605531. Photographer Michael Branstetter, uploaded by Default Group. Owned by CAS, San Francisco, CA, USA.
Stenamma leptospinum casent0604354 h 2 high.jpg
Worker. Specimen code casent0604354. Photographer Michael Branstetter, uploaded by Default Group. Owned by JTLC.

Nomenclature

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

  • leptospinum. Stenamma leptospinum Branstetter, 2013: 143, fig. 103 (w.) MEXICO (Oaxaca).
    • Type-material: holotype worker, 6 paratype workers.
    • Type-locality: holotype Mexico: Oaxaca, 22.4 km. SW Valle Nacional, 17.59112°N, 96.39138°W±20m., 1990 m., 13.viii.2009, MGB1391 (M.G. Branstetter); paratypes with same data.
    • Type-depositories: USNM (holotype); CASC, MCZC, MGBC, UCDC, UNAM, USNM (paratypes).
    • Distribution: Mexico.

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

Description

Worker

(10 measured) HL 0.80–0.93 (0.91), HW 0.70–0.87 (0.87), FLD 0.21–0.23 (0.23), PCW 0.04–0.08 (0.04), SL 0.69 –0.80 (0.75), EL 0.13–0.15 (0.15), ACL 0.62–0.68 (0.68), ML 1.02–1.18 (1.17), PrW 0.47–0.55 (0.55), PSL 0.17–0.22 (0.22), SDL 0.08–0.10 (0.10), PL 0.35–0.43 (0.42), PH 0.22–0.26 (0.26), PW 0.15–0.19 (0.19), PPL 0.19–0.25 (0.25), PPH 0.20–0.25 (0.25), PPW 0.19– 0.25 (0.24), MFL 0.79–0.92 (0.89), MTL 0.63–0.74 (0.73), CI 87–96 (96), SI 87–98 (87), REL 16–19 (18), FLI 26–31 (26), PSI 1.9–2.2 (2.2), MFI 88–97 (97), ACI1 63–66 (64), ACI2 85–92 (91).

Medium-sized species; general body color dark brown to brown, with append-ages brown to orange-brown; setae dark golden brown; mandible with 6 teeth, with two teeth nearest basal tooth smaller, often worn and indistinct; basal margin of mandible straight, without a basal notch or depression; mandible surface mostly smooth and shiny, with scattered piligerous punctae; anterior clypeal margin with a median emargination; median lobe of clypeus with a pair of faint longitudinal carinulae that diverge anteriorly, apex with a short transverse carinula, remainder of clypeus mostly smooth and shiny, with a few faint striae on median lobe; posterior extension of clypeus between antennal insertions of moderate to somewhat wide width (PCW 0.04–0.08); frontal lobes of moderate width (FLD 0.21–0.23, FLI 26–31), not completely obscuring torular lobes in full-face view; lateral margin of hypostomal bridge with a projecting subquadrate to broadly-rounded lobe that is usually visible behind mandible in profile, but some specimens with lobe reduced; head subcircular to oval-shaped (CI 87–96), posterior margin with a slight median depression; eye large (EL 0.13–0.15, REL 16–19), roughly oval-shaped, with 6–8 ommatidia at greatest diameter; face densely sculptured with a fan of longitudinal carinulae that extend outward from frontal lobes, lateral margins with shorter less densely spaced rugulae, interstices faintly punctate; scape of moderate length (SI 87–98), nearly reaching posterior margin of head when laid back; scape surface mostly smooth and shiny with scattered piligerous punctures; flagellum with a somewhat distinct 4-segmented antennal club; mesosoma densely sculptured; promesonotum mostly longitudinally carinulate, with some transverse carinulae wrapping around anterior declivity; mesopleuron and side of propodeum with irregular rugulae, rugoreticulae, and punctae; propodeal dorsum and part of declivity with transverse carinulae, remainder of declivity smooth and shining; promesonotum in profile low-domed and somewhat asymmetrical, with posterior slope longer and shallower than anterior slope; metanotal grove well demarcated and moderately deep, forming a rather smooth transition with promesonotum; anterior margin of propodeal dorsum in profile sometimes distinctly raised and separated from metanotal grove; propodeal spines long and rather slender (PSL 00.17–0.22, PSI 1.9–2.2), pointing anteroposteriorly and outward from body; petiole of moderate length (PL/HW 0.47–0.51), peduncle in profile somewhat slender; petiolar node in profile somewhat high (PH/PL 0.59–0.69), subconical and roughly symmetrical, with a well-defined apex that points vertically; postpetiolar node in profile usually somewhat anteroposteriorly compressed, with apex rounded and pointing vertically or slightly posteriad; anterior faces of petiolar and postpetiolar nodes smooth and shiny, posterior faces with punctae and a few rugulae, remaining surface of waist punctate; gaster mostly smooth and shiny, with scattered piligerous punctae and a few short striae around anterior constriction; most of body with rather long standing pilosity; scape with a uniform layer of subdecumbent to appressed setae; gaster with a layer of long suberect setae and a sparse layer of shorter decumbent setae; setae on legs mostly subdecumbent to appressed, with suberect setae on coxae and femoral venters.

Type Material

Holotype Specimen Labels

Holotype worker. MEXICO: Oaxaca, 22.4km SW Valle Nacional, 17.59112°N, 96.39138°W ±20m, 1990m, 13 Aug 2009, cloud forest, ex sifted leaf litter (M. G. Branstetter, collection MGB1391) USNM, specimen CASENT0605530. Paratypes: same data as holotype 1w, CASC, CASENT0605531, 1w, MGBPC, CASENT0605555, 1w, MCZ, CASENT0605532, 1w, UCDC, CASENT0605529, 1w, UNAM, CASENT0605533, 1w, USNM, CASENT0605554].

Etymology

The specific epithet leptospinum refers to the long (for Stenamma), slender propodeal spines of this species.

References

  • Branstetter, M. G. 2012. Origin and diversification of the cryptic ant genus Stenamma Westwood (Hymenoptera: Formicidae), inferred from multilocus molecular data, biogeography and natural history. Systematic Entomology 37:478-496. doi:10.1111/j.1365-3113.2012.00624.x.
  • Branstetter, M.G. 2013. Revision of the Middle American clade of the ant genus Stenamma Westwood (Hymenoptera, Formicidae, Myrmicinae). ZooKeys 295, 1–277. doi:10.3897/zookeys.295.4905

References based on Global Ant Biodiversity Informatics