Heliconius erato, Linnaeus, 1758

Brower, Andrew V. Z., 2018, Alternative facts: a reconsideration of putatively natural interspecific hybrid specimens in the genus Heliconius (Lepidoptera: Nymphalidae), Zootaxa 4499 (1), pp. 1-87 : 69-73

Hybrids between H. erato and H. himera from western Ecuador and Peru

For most of the 20th century, H. himera was viewed as a race of H. erato ( Eltringham 1916; Brown 1979), and from a phylogenetic perspective, H. himera is nested among various races of a paraphyletic H. erato ( Brower 1994b; Hines et al. 2011; Supple et al. 2015; Van Belleghem et al. 2017). These two taxa are parapatric in southern Ecuador, where H. erato cyrbia prefers wetter, lower forest, and H. himera occurs in higher, drier Acacia scrub, however they abut in a narrow hybrid zone ( Jiggins et al. 1996). Descimon & Mast de Maeght (1984) suggested a "semispecies" relationship between the two, due to a deficit of observed hybrid specimens from numbers expected if the parental forms were mating at random. Based on this observation, Mallet (1993, p.245) opined, "it is more sensible to regard H. himera as a good species." Mallet (1995) proposed the "genealogical cluster concept" of species to accommodate taxa such as H. himera , which while still hybridizing at appreciable frequency with its sister taxon appears to have reached a tipping point at which homogenizing gene flow does not occur. We will return to Mallet's species concept in the discussion.

Mallet et al. (2007) listed a series of 52 hybrid specimens between H. erato cyrbia and H. himera (three exemplars of which are shown below: Figs. 158–160 ). The genetics of wing pattern inheritance were experimentally worked out by Jiggins et al. (1996), and there is no doubt that these specimens are legitimate hybrids. Thus, hybrids #101-152 are given the following collective scores:

Identity: 1.0

Authenticity: 1.0

Overall reliability: 1.0

Identity: 1.0

Authenticity: 1.0

Overall reliability: 1.0

Identity: 0.5

Authenticity: 0.2

Overall reliability: 0.1

Hybrid #155 (not illustrated in Mallet et al. 2007). Peru: San Martín, Rodriguez de Mendoza-Omia km 11, 1986, leg. J. Mallet (Mallet collection). Interpreted by Mallet et al. (2007) as H. himera (fig. 157) x H. erato favorinus (fig. 161). This specimen cannot be independently evaluated from the evidence presented. Habeas corpus !

Identity: 0.

Authenticity: 1.0

Overall reliability: 0.0

Identity: 0.9

Authenticity: 0.8

Overall reliability: 0.72

Identity: 1.0

Authenticity: 0.9

Overall reliability: 0.9

Figures

FIGURE 158. Hybrid #111 (dorsal, ventral). H. erato cyrbia (Fig. 156) x H. himera (Fig. 157) F1 (dorsal, ventral). Ecuador: El Oro, Guayquichuma site 4, 1993 (Neukirchen collection, FLMNH). The yellow forewing bands are replaced with red, but otherwise the specimen looks like H. himera.

FIGURE 159. Hybrid #110 (dorsal, ventral). H erato cyrbia (Fig. 156) x H. himera (Fig. 157) backcross to H. himera. Ecuador: El Oro, Guayquichuma site 4, 1993. leg. S. Attal (Neukirchen collection, FLMNH). There is a faint pinkish edge on the distal margin of the yellow forewing band.

FIGURE 160. Hybrid #117(dorsal, ventral). H erato cyrbia (Fig. 156) x H. himera (Fig. 157) backcross to H. erato. Ecuador: El Oro, Guayquichuma site 4, 1993. leg. S. Attal (Neukirchen collection, FLMNH). Both H. himera's red HW band and the yellow HWV stripe of H. erato cyrbia are expressed in this individual.