The species Smithistruma microthrix shows geographic variation within Costa Rica.

The figure above shows worker headlength plotted against head width. Numbers in the plot area are elevations where specimens were collected in 100's of meters (i.e. "15" = 1500m). Elevations of 1500 to 1600m are from Monteverde cloud forest. Elevations from 800 to 1400m are from the Penas Blancas Valley just east of Monteverde. Elevations from 100 to 500 are from La Selva and the contiguous portion of Braulio Carrillo National Park (Zona Protectora) just above La Selva.

Color is also variable. The larger specimens from Monteverde (head width greater than 0.56mm) and the two specimens from La Selva (100m) are dark gray. The remaining specimens are orange in color. Thus there is weak evidence for discontinuities and discrete locally sympatric forms. For example, one Monteverde specimen is smaller and orange, strikingly different from the other Monteverde collections, and more similar to lowland specimens. La Selva and vicinity has both orange and gray forms. The meaning of this character variation remains unknown.

Measurement data:

Headwidth Headlength Specimenbarcode Locality

microthrix
0.594 0.722 INBIOCRI001283680 Monteverde 1500m
0.634 0.777 INBIOCRI001283683 bottom worker, Monteverde 1500m
0.619 0.751 INBIOCRI001283683 top worker, Monteverde 1500m
0.579 0.730 INBIOCRI001281350 bottom, Monteverde 1600m
0.608 0.745 INBIOCRI001281350 top worker, Monteverde 1600m
0.633 0.773 INBIOCRI001283714 Monteverde, 14-1600m
0.570 0.729 INBIOCRI001283682 Monteverde, 14-1600m
0.580 0.741 INBIOCRI001283687 Monteverde 1500m
0.526 0.657 INBIOCRI001283688 Monteverde 1500m
0.549 0.700 INBIOCRI001281759 Penas Blancas 1400m
0.535 0.703 INBIOCRI001283712 bottom worker, Penas Blancas 1000m
0.534 0.696 INBIOCRI001283712 top worker, Penas Blancas 1000m
0.530 0.646 INBIOCRI001283713 Penas Blancas 800m
0.528 0.653 INBIOCRI001283942 Penas Blancas 800m
0.513 0.641 INBIOCRI001283685 bottom worker, Zona Protectora 500m
0.514 0.636 INBIOCRI001283685 top worker, Zona Protectora 500m
0.526 0.647 INBIOCRI001283686 bottom worker, Zona Protectora 300m
0.537 0.666 INBIOCRI001283686 top worker, Zona Protectora 300m
0.540 0.657 INBIOCRI001258888 La Selva
0.516 0.648 INBIOCRI001258891 La Selva

crassicuspis
0.504 0.645 INBIOCRI001283708 Penas Blancas 800m
0.502 0.645 INBIOCRI001283709 Penas Blancas 800m
0.495 0.635 INBIOCRI001283941 Penas Blancas 800m
0.465 0.608 INBIOCRI001237688 bottom worker, La Selva
0.481 0.603 INBIOCRI001237688 top worker, La Selva

stauroma
0.568 0.699 INBIOCRI001283710 Penas Blancas 800m
0.564 0.713 INBIOCRI001283707 Penas Blancas 800m
0.511 0.622 INBIOCRI001259534 La Selva
0.500 0.611 INBIOCRI001259536 La Selva
0.479 0.591 INBIOCRI001259537 La Selva

Page author: John T. Longino longinoj@evergreen.edu
Last modified: 07/23/1996