Pogonomyrmex theresiae Forel 1899

 

Pogonomyrmex theresiae Forel, 1899b: 303 (worker); Forel, 1899c: 274 (worker redescribed as new). Syntypes examined: 1 worker [ZSM], ECUADOR, Guayas: Estero Salado near Guayaquil (ZSM worker is the HOLOTYPE, by monotypy).

 

      Worker

      Diagnosis.  The combination of: (1) absence of superior propodeal spines (small tubercles or denticles only), (2) transverse rugae on dorsum of postpetiole, and (3) lacking longitudinal striae on first gastral tergum uniquely characterize this species.

      Measurements – holotype, by monotypy. HL 1.45; HW 1.46; MOD 0.30; OMD 0.39; SL (scapes missing); PNW 1.01; HFL 1.42; ML 1.67; PW 0.36; PPW 0.52. Indices: SI N/A; CI 100.69; OI 20.55; HFI 97.26.

Description. Head quadrate (CI = 100.69), broadest just posterior to eye; posterior margin weakly convex in full-face view.  Longitudinal cephalic rugae prominent, slightly wavy, in full-face view median rugae diverging slightly towards posterior corners of head.  In side view, rugae converging near midway between posterior margin of eye and vertex; vertex weakly to moderately rugose.  Interrugal spaces on vertex smooth, strongly shining; cephalic interrugal spaces moderately granulate, weakly shining.  Anterior margin of clypeus concave; dorsal surface with numerous subparallel longitudinal rugae.  Mandibles with six teeth; mandibular dorsum coarsely striate.  Numerous moderately long, curved, bristle-like, cream to light yellowish hairs project from basolateral margin of mandibles.  MOD = 0.21x HL.  Eyes in profile situated near middle of head, OMD = 1.30x MOD.  Scapes missing; scapes not reaching vertex as per Forel (1899b).  Psammophore moderately well developed.

Mesosomal profile moderately convex; all mesosomal surfaces with prominent rugae.  In side and dorsal views, humeral shoulders enlarged, angulate.  Dorsum of promesonotum and sides of pronotum rugoreticulate to vermiculate.  Mesopleura with irregular rugae angling posterodorsally.  Dorsum of propodeum with irregular rugae to rugoreticulate.  Propodeal spines consisting of small denticles or tubercles.  Inferior propodeal spines weakly developed, consisting of a small, broadly rounded triangular process.  Propodeal spiracles narrowly ovate.  Interrugal spaces on mesosoma moderately granulate, dull to weakly shining.  Legs weakly coriarious, weakly shining to smooth and shining.

Petiolar peduncle about as long as petiole, anteroventral margin with a bluntly rounded triangular process.  In side view, posterior surface of petiole weakly convex; petiolar node asymmetrical with anterior surface slightly shorter than posterior surface, apex of node weakly rounded to subangulate.  In dorsal view, petiolar node longer than broad, narrowest at posterior margin, gradually widening to spatulate anterior margin; posterior surface with moderately strong wavy to irregular transverse, sometimes discontinuous rugae.  Dorsum of postpetiole convex in profile; in dorsal view, widest at or near posterior margin, narrowing to anterior margin; maximal width about equal to length; dorsum and sides with wavy transverse rugae that are slightly weaker, more closely spaced, and more regular than those on petiole.  Interrugal spaces on posterior surface of petiole and dorsum of postpetiole weakly granulate, weakly shining to smooth and shining.  Base of first gastral tergum weakly coriarious, shining, remainder smooth, strongly shining.

Very short, erect, whitish pilosity sparse on head.  Scapes missing; as per Forel (1899b), scapes with a few scattered oblique, short, stiff, yellowish hairs (and a few streaks).  Mesosoma, petiole, postpetiole, and dorsum of gaster mostly lacking hairs except for several short, suberect hairs on legs, mesopleura, posterior declivity of propodeum, and ventral surface of postpetiole.  Head ferruginous orange; mesosoma slightly darker ferruginous orange; petiole, postpetiole, gaster, and legs blackish-orange.

      Queen. Unknown.

      Male. Unknown.

Additional material examined. None.

      Etymology. Forel dedicated the naming of this species to the Royal Highness, the Princess Therese von Bayern.  

 

Discussion.  Pogonomyrmex striatinodis the only congener known to occur in Ecuador; it is only known from mesic forest habitats, lacks a psammophore and has long superior and inferior propodeal spines, whereas P. theresiae has a moderately well developed psammophore and lacks superior and inferior propodeal spines.  Pogonomyrmex naegelii might also occur in Ecuador; P. theresiae is easily distinguished by transverse rugae on the posterior face of petiole and dorsum of postpetiole (rugoreticulate in P. naegelii) and absence of propodeal spines (present in P. naegelii).

 

BIOLOGY

Nothing is known about the biology of P. theresiae, which appears to be known from one worker that was collected over 100 years ago at Estero Salado near Guayaguil, Ecuador.  Guayaguil is currently the largest and most populous city in Ecuador, such that the type locality is probably urbanized or destroyed.  However, it might be productive to search for this species along roadsides in agricultural areas surrounding Guayaguil, as both North and South American congeners commonly occur in such habitats.  Other areas in which to search for P. theresiae would seem to be those that have a climate similar to that of Guayaguil (tropical savanna); these areas include western portions of the provinces of Guayas and Manabí and the southernmost part of Esmeraldas (see also Lattke, 2006).

 

REFERENCES

 

Forel, A. (1899a) Trois notices myrmécologiques. Annales de la Société Entomologique de Belgique, 43, 303-310.

Forel, A. (1899b) Von Ihrer Königl. Hoheit der Prinzessin Therese von Bayern auf einer Reise in Südamerika gesammelte Insecten. 1. Hymenoptera. a. Fourmis. Berliner Entomologische Zeitschrift, 44, 273-276.

Lattke, J.E. (2006) A new species of Pogonomyrmex (Hymenoptera: Formicidae) from gallery forests of the Orinoco watershed, Venezuela. Myrmecologische Nachrichten, 8, 53-57.