Pheidole scalaris

Longino (1997) found P. scalaris in both seasonal dry forest and evergreen forest. The workers were recruited to baits on the forest floor.

Identification
See the description in the nomenclature section.

Distribution
Atlantic and northern Pacific lowlands of Costa Rica; and Arima Valley, Trinidad. (Wilson 2003)

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Ecuador, Trinidad and Tobago, Venezuela.

Nomenclature

 *  scalaris. Pheidole scalaris Wilson, 2003: 643, figs. (s.w.) COSTA RICA.

Description
DIAGNOSIS Close to Pheidole transversostriata but distinguished from it and other members of the transversostriata group by the broad occipital zone of rugoreticulum on the dorsal surface of the head of the major, surmounting a wide “ladder” of parallel transverse carinulae that reach the frontal lobes, where they curve anteriorly to the ends of the lobes; also, the promesonotal dorsum is completely covered by transverse carinulae. Also, see the distinctive color of the minor (below).

This species is possibly synonymous with P. transversostriata var. nigridens Forel of Colombia, which has been provisionally synonymized with transversostriata; nigridens has rugoreticula on the occipital corners and more carinulae on the pronotal dorsum, and is intermediate between Pheidole scalaris and transversostriata. However, scalaris also differs from transversostriata by the more elongate head of the major (Head Length 1.3! Head Width versus 1.2X in transversostriata) and smooth sides of the pronotum of the minor.

MEASUREMENTS (mm) Holotype major: HW 0.64, HL 0.84, SL 0.32, EL 0.10, PW 0.36. Paratype minor: HW 0.42, HL 0.46, SL 0.36, EL 0.08, PW 0.26.

COLOR Major: concolorous medium yellow.

Minor: overall light brownish yellow, with medium brown vertex, occiput, and dorsum of promesonotum, and medium yellow appendages.



'''Figure. Upper: holotype, major. Lower: paratype, minor. Scale bars = 1 mm.'''

Type Material
COSTA RICA: La Selva Biological Station, near Puerto Viejo, Heredia, col. Stefan Cover.

Etymology
L scalaris, of a ladder, alluding to the strong ladder-like pattern on the dorsum of the major head.