Description of two new species of the genus Cacopsylla Ossiannilsson, 1970 (Hemiptera, Psylloidea) from northern Fennoscandia recognized by morphology, cytogenetic characters and COI barcode sequence

Abstract

Based on chromosomal, molecular and morphological analyses, two new Cacopsylla Ossiannilsson, 1970 species are described, C. lapponica S. Nokkala & Ch. Nokkala, sp. nov. and C. borealis S. Nokkala et Ch. Nokkala, sp. nov. (Hemiptera, Psylloidea). C. lapponica is a rare bisexual alpine species living on Vaccinium uliginosum Linnaeus, 1753 above tree line on northern hills, where it forms sympatric populations with C. myrtilli W. Wagner, 1947. So far, the species has been found in northern Finland, Utsjoki and Kilpisjärvi, and in northern Sweden, Abisko. The chromosome number in males is 2n = 12+X(0), characteristic of psyllids. The species is easily distinguished from C. myrtilli by its conspicuously smaller size mainly due to difference in wing size. Additional morphological differences are found in the length of antennae, female genital plates and male parameres. C. borealis, in turn, is a relatively common apomictic parthenogenetic species with 5n = 60 + XXXXX living on the same host plant, Ledum palustre Linnaeus, 1753, as C. ledi (Flor, 1861) and occasionally forming sympatric populations with it. No males have been recorded in C. borealis. Its distribution range reaches at least from northern Fennoscandia to Lake Baikal in the East. C. borealis can be distinguished from C. ledi by differences in the length and width of antennae, dark brown markings on the wing and female terminal structures. For molecular analysis, a 638 bp fragment of the mitochondrial COI gene was sequenced. C. lapponica differs from the cohabitating C. myrtilli by 20 fixed nucleotide substitutions (uncor rected p-distance 3.13 %), while C. borealis differs from C. ledi by 21 fixed nucleotide substitutions (uncorrected p-distance 3.29 %). Molecular phylogeny construction (ML and BI) reveals two highly divergent clades, one comprising two bisexual species, C. lapponica and C. fraudatrix Labina & Kuznetsova, 2012, and the other clade comprising the parthenogenetic species C. borealis, C. myrtilli, and C. ledi. Within this clade, C. borealis is more closely associated with C. myrtilli than with C. ledi.

Comparative analysis of chromosome numbers and sex chromosome systems in Paraneoptera (Insecta)

“…In a recent classification of Psyllinea ( Burckhardt and Ouvrard 2012 ), as many as 8 families have been recognized incuding Aphalaridae , Carsidaridae , Calophyidae , Homotomidae , Liviidae , Phacopteronidae , Psyllidae , and Triozidae . Cytogenetically, approximately 220 species from 55 genera (about 5.3% and 27% of their total number, respectively) have been investigated to date ( Maryańska-Nadachowska and Głowacka 2005 ; Labina et al 2007 ; Kuznetsova et al 2012 ; Nokkala et al 2019 ; for other references, see review of Maryańska-Nadachowska 2002 ). Karyotypes, mainly in terms of chromosome number and sex chromosome system, are currently known for all families with the exception of the tropical most basal family Phacopteronidae ( Cho et al 2019 ).…”

“…With rare exceptions ( Labina et al 2009 ; Nokkala et al 2013 , 2015 , 2019 ), psyllids reproduce bisexually. The bisexual species have diploid chromosome numbers varying between 7 and 27 in males with a distinct mode at 25, suggesting that this is the ancestral count of the Psyllinea.…”

“… C. borealis is a pentaploid species (2n=5x=60A+XXXXX) with apomictic parthenogenetic reproduction. No males have been recorded in C. borealis so far ( Nokkala et al 2019 ). The third species, Cacopsylla ledi (Flor, 1861), is widely distributed throughout Fennoscandia, Central Europe, and Russia; it occasionally forms sympatric populations with C. borealis .…”

Introduction to the study of chromosomal and reproductive patterns in Paraneoptera

“…In the laboratory, each of those specimens was dissected; the abdomen was immersed in the Carnoy's fixative while the head and thorax part was stored in alcohol for subsequent sequencing. This allowed both chromosomal and haplotype (DNA barcoding) analyses of the same individual, which was very important for the purposes of accurate taxonomic identification of individuals (Nokkala et al 2015(Nokkala et al , 2017(Nokkala et al , 2019.…”

The highly rearranged karyotype of the hangingfly Bittacus sinicus (Mecoptera, Bittacidae): the lowest chromosome number in the order

“…The chromosomal morphology may provide substantial information related to structural rearrangements, which may contribute to the increased level of divergence among taxa (Rieseberg and Burke 2001;Navarro and Barton 2003;Butlin 2005). Such studies have been well documented in many insect groups, including aquatic bugs (Stoianova et al 2020), psyllids (Nokkala et al 2019), bush crickets (Kociński et al 2018), beetles (Dutrillaux and Dutrillaux 2019), butterflies (Dincă et al 2011), warrior wasps (Menezes et al 2019), and ants (Pereira et al 2018). In Bittacidae, however, the cytogenetic information is poorly documented, with only six species reported to date (Matthey 1950;Atchley and Jackson 1970;Hua 2017, 2019).…”