Melitaea pseudornata, Munoz Sariot & Sanchez Mesa, 2019

Hinojosa, Joan C., Tóth, János P., Monasterio, Yeray, Mesa, Luis Sánchez, Muñoz Sariot, Miguel G., Escobés, Ruth & Vila, Roger, 2022, Integrative Taxonomy Reveals a New Melitaea (Lepidoptera: Nymphalidae) Species Widely Distributed in the Iberian Peninsula, Insect Systematics and Diversity 6 (2), pp. 1-9 : 7

M. pseudornata and M. phoebe ,Two

Interacting Species

Mitochondrial DNA ( Figs. 2A,B ) showed that M. pseudornata shared two haplogroups (here, groups of haplotypes linked by two

or fewer mutations) with M. phoebe . One of the shared haplogroups, Haplogroup 1, is exclusive to Iberia. The second shared haplogroup, Haplogroup 2, was also found in M. phoebe from all Europe (including Iberia) and in M. ornata . Considering that M. ornata conserves a well diverged COI lineage in the Balkan Peninsula and eastwards (Haplogroup 3), the fact that in other parts of Europe this species is clustered in the same haplogroup with M. phoebe and M. pseudornata while nuclear markers differentiate them suggests mitochondrial introgression. Thus, M. ornata would have partially lost its original mtDNA in favor of an introgressed mtDNA presumably coming from M. phoebe , a scenario already proposed by Tóth et al. (2017). The same situation may apply to M. pseudornata , whose mtDNA could have been completely erased after the introgression events with M. phoebe —as occurred in other Iberian species such as Iphiclides feisthamelii ( Gaunet et al. 2019) . Overall, we cannot determine from these data how common hybridization between M. phoebe and M. pseudornata might be at present but, given that they share two well-differentiated haplogroups, introgressive hybridization seems to have occurred at least twice in the past.

Past hybridization between M. phoebe and M. pseudornata could have had an impact on the morphology of the larvae and the adults. A sign of this can be the presence, in populations of northern Iberia, of the orange lateral stripe in the caterpillars, very similar to those present in the Iberian M. phoebe ( Fig. 4 ); these stripes are absent in M. ornata ( Russell and Tennent 2016) . Regarding the adults, a combination of traits of the wing underside such as the premarginal markings and color tone of the hindwings and are considered to be relatively useful to distinguish between M. ornata and M. phoebe ( Russell and Tennent 2016) . However, between the Iberian M. phoebe and M. pseudornata , these traits are regularly shared (Supp Fig. S4 [online only]). Furthermore, no other external traits seem to unambiguously differentiate the adults of M. pseudornata and M. phoebe .

M. pseudornata populations may also be affected by ecological character displacement regarding the larval host plant. In the Baetic System, M. pseudornata females are known to oviposit (or L 1 larvae were found) on Carduncellus Adans , Carduus L., and Cirsium Mill. , whereas M. phoebe oviposits on Centaurea L. Contrastingly , in central Navarre, an area where only M. pseudornata has been found, we only observed larvae (including L1) feeding on Centaurea jacea . This behavior could be influenced by a potential competitive pressure caused by the more generalist M. phoebe , a hypothesis already suggested by Tóth et al. (2015) for M. ornata .

Figures

Fig. 2. A. Haplotype network of the Melitaea phoebe species group based on the barcode fragment of the COI gene.The area of the circles is proportional to the number of sequences they represent. B. European distribution of the three haplogroups of Melitaea pseudornata stat. nov., M. phoebe and Melitaea ornata. C. Bayesian inference phylogeny obtained using a partitioned alignment of the nuclear genes EF-1ɑ, MDH, wg and RPS5. Posterior probabilities at species-level and for higher relationships are indicated, and scale units are presented in substitutions per site.

Fig. 4. Pictures of the northern and southern forms of Melitaea pseudornata stat. nov. and of Melitaea phoebe. An approximate distribution of M. pseudornata based on the sequenced specimens is given; populations in eastern and southern Iberia are apparently more scattered and restricted to mountain ranges.