Indra subspecies in Utah
The Northeastern Area

Now, lets look at northeastern Utah and an intergradation zone which was recently discovered. In this region the postmedian wing bands of P. i. minori continue to become wider in the northern sector of the Tavaputs Plateau. By extreme northeastern Utah, many individuals have quite wide postmedian wing bands closely resembling the nominate subspecies, but many retain their large size, extensive hind wing blue patches, and the long tails typical of minori. Eventually these minori populations grade into P. i. indra-like morphs near the Wyoming border. This entire area appears to be a zone of intergradations between the two subspecies via secondary contact. Some of the specimens from this region are very beautiful (next photo).

A beautiful mix of P. i. minori and P. i. indra characteristics. (This is a large specimen measuring 2 15/16 across forewing tips.)

The degree of variation within this transition region is phenomenal as illustrated in the next two photo. There is a full range of variation between extremes from P. i. minori-like individuals to P. i. indra-like individuals.

Adult phenotypic extremes from the northeastern Utah area.


Six adults grading from minori-like toindra-like in northeastern Utah. These specimens are larger and have longer tails than nominate Indra in Colorado and Wyoming.

Unlike the nominate race of Colorado, bivoltinism is common in this zone of intergradation-a result of adaptation to the LFP (C. terebinthinus) which retains some green vegetation all Summer. Many of the 5th instars in northeastern Utah are pink, which is likely caused by minori genes from the south. Third and 4th instars also resemble minori, and some are unusual looking (see photos below).

3rd or 4th instar from northeastern Utah. Strange looking 4th instar from northeastern Utah.

In conclusion, there appears to be considerable influence from minori genes all the way to the Wyoming/Utah border which is further north than has be previously documented. The nearest known population of pure minori is just 40 miles to the southwest of Vernal, Utah.

Within this zone of intergradation some "rare" individuals look much like nominate Indra, including smaller size, stubby tails and the broad postmedian wing bands as illustrated below.

Comparison of P. i. indra (top) with a P. i. indra-like adult from the northeastern Utah zone of intergradation.

There is some infusion of minori genes even to the Wyoming border as illustrated below. This is a P. i. indra-like adult with some minori characteristics such as narrower wing bands and tails of intermediate length.

Specimen of P. i. indra-like adult with some minori characteristics taken 4 miles from the Wyoming border in northeastern Utah.

I suspect that this intergradation zone is quite wide--as I have illustrated on the range map--possibly extending well across western Colorado to maybe as far as Steamboat Springs.

There is much work to be done in this area of northwestern Colorado, and a lack of herbarium records makes the Indra search difficult. I am interested in correspondence with anyone who has Indra LFP records or Indra Swallowtail population records from the area marked Integradation Zone ? on the map. Please correspond by phone: (801) 863-8607 or email:

Northwest Utah