Species identification of the psammophilous tenebrionid beetles Phaleria acuminata Küster, 1852 and Phaleria bimaculata (Linnaeus, 1767) from central Mediterranean beaches: geometric morphometrics and molecular insights from species to population level

Abstract

Dominating global arid environments, from desert to coastal dunes, most Tenebrionidae are highly specific in their habitat preferences and display limited dispersal potential, thus exhibiting a remarkable degree of regional genetic and morphological differentiation. The tenebrionid genus Phaleria is speciose and widely distributed, with P. acuminata and P. bimaculata having a wide Mediterranean distribution, with numerous morphological differentiations at population level, often described as different taxa of doubtful taxonomical significance. In order to investigate the variability of the central Mediterranean populations of P. bimaculata and P. acuminata and to compare the results obtained with different identification techniques, these species were sampled on sandy beaches in Sicily (southern Italy) and on circum-Sicilian and Maltese islands. Collected samples were studied through the application of geometric morphometrics and the sequencing of a fragment of the mitochondrial COII gene. Geometric morphometrics and molecular analyses gave congruent results, allowing a sound separation of the two species. At the population level, the two species showed different patterns. P. acuminata showed a remarkable morphological and molecular homogeneity throughout the sampled area. Conversely, two well-characterized subclades were detected within P. bimaculata, and within the two lineages, a low-to-absent inter-populations differentiation was observed, in spite of the physical isolation of the sampled sandy beaches and of their geographical distance. These two P. bimaculata lineages, hereby named ''Tyrrhenian sub-clade'' and ''Southern sub-clade,'' might be compatible with the hypothesis of subspecific status already proposed for the populations from the Aeolian archipelago (as P. bimaculata marcuzzii Aliquò). Keywords Sandy beaches Á Phaleria spp. Á Central Mediterranean Á Species delimitation Á Molecular systematics Á Geometric morphometrics Communicated by A. Schmidt-Rhaesa.

Does size matter for horny beetles? A geometric morphometric analysis of interspecific and intersexual size and shape variation in Colophon haughtoni Barnard, 1929, and C. kawaii Mizukami, 1997 (Coleoptera: Lucanidae)

“…2). Only the left side of structures were digitised to avoid bias caused by bilateral asymmetry (Marrone et al 2014). Mandibles were analysed for males only as female mandibles were too small to reliably identify homologous landmarks.…”

An integrative approach challenges species hypotheses and provides hints for evolutionary history of two Mediterranean freshwater palaemonid shrimps (Decapoda: Caridea)

“…So did the material used in Pizzo et al's (2011) study. In contrast, Marrone et al (2013) observed two lineages of the terrestrial tenebrionid beetle, Phaleria bimaculata, but its distribution in Sicily corresponded to the ancient geological division of the island into the African-and European-derived parts. Taking into account the fact that Sicilian shrimps did not differ morphologically from the peninsular ones, it is worth noting that the genetic outcomes of our study reported only one haplotype (mtH12) in common between shrimps collected in central AP (14%) and Sicily (86%).…”

“…Although geometric morphometric studies combined with genetics have often been conducted on invertebrates, including arthropods (e.g. Silva et al 2010;Marrone et al 2013;Zinetti et al 2013;Marchiori et al 2014;Kamimura et al 2020), such an approach has not previously been used on caridean shrimps. Consequently, our study is the first to combine these methods for this group of crustaceans.…”