Leptothorax (Myrafant) andersoni Mackey, 2000

Leptothorax (Myrafant) andersoni
Mackay, 2000 : (in press).
Diagnosis. This is a small, concolorous yellow brown species with a 12-segmented antenna. The entire head and mesosoma are coarsely and densely punctate. The propodeal spines are well developed, but small (Fig. 83). The petiolar node is blunt in profile. The gaster has punctures on the basal third of first gastral tergum.
Description.
Worker measurements (mm):
HL 0.55 - 0.64 HW 0.46 - 0.52 SL 0.43 - 0.47 EL 0.13 - 0.14
WL 0.64 - 0.68 PW 0.14 - 0.16PL 0.18 - 0.19PPW 0.22 - 0.23 PPL 0.16 - 0.17.
Indices:
CI 81 - 84 SI 73 - 78 PI 78 - 84 PPI 130 - 135.
Mandibles with 5 teeth, only apical 3 well defined; anterior border of clypeus convex, clypeus with well formed median carina plus several lateral carinae; sides of head broadly and weakly convex; vertex weakly concave; eyes small, 8 or 9 facets in greatest diameter; antennae with 12 segments; mesosoma without any sutures breaking surface; propodeal spines small, but well developed and acute (Fig. 51); petiole with well developed subpeduncular tooth, acute and with flange which extends posteriorly at least half length of petiole, anterior petiolar face concave, posterior face convex, petiolar node blunt in profile.
Erect hairs on all surfaces, except legs and antennae, up to 0.8 mm in length; decumbent pubescence sparse, present on legs and antennae.
Sculpture consisting of closely set, dense punctures on all surfaces of head (except middle of underside of head), mesosoma, petiole and postpetiole, and gaster with punctures over basal third of first gastral tergum (Fig. 5).
Color light yellowish brown. (Mackay, 2000).
Figures. Figs. 14 & 83 (Mackay, 2000).
Etymology. Named in honor of the collector, Robert Anderson, who has provided me with abundant material collected from litter. (Mackay, 2000).
Discussion. This species is easily recognized by the punctures on the first gastral tergum. It can be separated from other species with a sculptured gaster, such as L. obliquicanthus, L. silvestrii and L. rugosus, by the small propodeal spines. Leptothorax rugosus and L. silvestrii have coarse rugae on the dorsum of the mesosoma, L. andersoni is densely punctate in this region, without any evidence of rugae. Leptothorax obliquicanthus has kidney shaped eyes, L. andersoni has round eyes. There is no chance of confusing this species with L. hispidus, as the outline of the mesosoma is continuous, without the depressed mesopropodeal suture found in L. hispidus. If the sculpture on the dorsum of the gaster is too fine to be noticed, L. andersoni would key with difficulty to L. terrigena. It could be separated from the latter species as the node of the petiole is obliquely truncate (Fig. 84), whereas the node of the petiole of L. terrigena is broadly rounded (Fig. 180). Additionally, close inspection of the gaster should reveal the fine sculpture.
This species could be confused with other pales species found in the Chihuahuan Desert, including L. bestelmeyeri, L. cokendolpheri, L. coleenae, and L. liebi. See the discussion of L. coleenae for hints on how to separate these species. (Mackay, 2000).
Keys to species. Neotropical (Mackay, 2000).
Taxonomy. Species complex: andersoni
Biology. All four workers were collected in mixed hardwood leaf litter (Mackay, 2000).
Distribution. Known only from Big Bend National Park in southwestern Texas (Fig. 3). (Mackay, 2000).

Type series. Holotype worker (MCZC) and two paratype workers (CWEM, USNM), USA, Texas, Brewster Co., Big Bend National Park, Cattail Falls, 6-ix-1988, R. Anderson. (Mackey, 2000)

Material examined. Four workers, including type series and a worker collected from Texas, Brewster Co., Big Bend National Park, Pine Canyon, 6-ix-1988, R. Anderson (CWEM). (Mackey, 2000) Maps Map 3 (Mackay, 2000).


Go up | Introduction | SIWeb
© American Museum of Natural History, January 16, 2000; Acknowledgments
- This page is maintained by Donat Agosti