New Contribution to the Knowledge on the Chromosome Numbers of Turkish Cerambycidae (Coleoptera)

Information on the karyotypes of Turkish species of Cerambycidae is scanty. Our study contributes to the knowledge of the karyological data (chromosomal number and mechanism of sex determination) of five Turkish longicorn beetles; karyotypes of four taxa, one endemic, are described for the first time and for the remaining one, Purpuricenus budensis (Götz, 1783), the previously published chromosome count is confirmed. The chromosome number of Purpuricenus desfontainii inhumeralis Pic, 1891 and Purpuricenus budensis (Götz, 1783) (Cerambycinae, Trachyderini) was found to be 2n = 28 (13 + Xyp); Clytus rhamni Germar, 1817 and Plagionotus floralis (Pallas, 1773) (Cerambycinae, Clytini) 2n = 20 (9 + Xyp); and the endemic Dorcadion triste phrygicum Peks, 1993 (Lamiinae, Dorcadionini) 2n = 24 (11 + Xyp). In view of the paucity of data available until now, our study is important for both to improve the poor karyological knowledge of Turkish Cerambycidae and to provide an incentive for other researchers.

In the present paper we report the results of chromosomal observations on 5 taxa belonging to three tribes (Trachyderini, Clytini and Dorcadionini) of two subfamilies (Cerambycinae and Lamiinae) to further extend our karyotypic knowledge of Turkish Cerambycidae. New data are presented for four taxa: Purpuricenus desfontainii inhumeralis, Clytus rhamni, Plagionotus floralis, and Dorcadion triste phrygicum, while for Purpuricenus budensis we confirm the data previously obtained by OKUTANER (2011).
The genus Purpuricenus is distributed in all zoogeographical regions except the Neotropical one. To date, about 60 species have been identified in three re-gions, viz. Palaearctic, Nearctic, and Indomalaya regions, in which the genus is mostly distributed (MACRAE 2000;GHATE et al. 2006); 46 of those are from the Palaearctic region and 12 are from Turkey (OZDIKMEN & TEZCAN 2020). Many taxonomic changes have been made in the genus Purpuricenus, especially in the Palaearctic region, during the last 50-60 years (KADLEC 2006).
The genus Clytus is represented in the world by about 50 species. In the Palaearctic region by 22 species and in Turkey by 12 species, 4 of them being endemic. The genus Clytus is a group that probably needs to be separated into new genera and subgenera (OZDIKMEN 2012;OZDIKMEN & TURGUT 2009a). For instance, SAMA (2005) described Sphegoclytus as a separate Clytini genus by excluding it from Clytus.
The genus Plagionotus is represented in the world by some 12 species, in the Palaearctic region by 11 species, and in Turkey by 5 species (OZDIKMEN 2012;OZDIKMEN & TURGUT 2009b;OZDIKMEN 2007). Clytus and Plagionotus seem to be closely related and subjected to taxonomic revisions. For example, Clytus latreillei was described by Laporte and Gory (1836) but later transferred to the genus Plagionotus by Aurivillius (1912).
Dorcadion triste phrygicum Peks, 1993 is included in the subgenus Maculatodorcadion Breuning, 1943. The genus Dorcadion is represented in the world by about 382 species and in Turkey by 192 species, 151 of them are endemic while the subgenus Maculatodorcadion is represented both in the world and in Turkey by 4 species, 3 of them endemic (OZDIKMEN & KOCAK 2015). Note that it is not easy to differentiate and identify Dorcadion species (ONALP 1991).

Material and Methods
Adult cerambycid males from five taxa of cerambycid beetles were collected from the environs of the Antalya, Eskiºehir, and Ankara provinces between March and September between 2015 and 2016. Karyotype determinations were made from acetic acid squashes of testes tissues taken directly from live individuals anaesthetized with ethyl acetate prior to abdomen dissection. The number of specimens were as follows: Purpuricenus budensis -6, Purpuricenus desfontainii inhumeralis -5, Clytus rhamni -8, Plagionotus floralis -11, and Dorcadion triste phrygicum -2. The procedure used in making the chromosome preparation was the squash method developed by RO¯EK (1994) with slight modifications (LACHOWSKA et al. 1996;HOLECOVÁ et al. 1999;RO¯EK & HOLECOVÁ 2000). Observation of chromosomes was done at 100x magnification, using a Leica DMLB 2 photomicroscope coupled with a Leica DFC320 camera and photographs were taken of the best well-spread metaphase cells.

Results and Discussion
The chromosomal formulae of the five studied taxa and those of other species previously analyzed by different authors and belonging to the same tribes as ours are given in Table 1. The sexual pair in males has a configuration in the shape of a parachute (Xy p ) for all investigated taxa. Additionally, spermatogonial metaphases are illustrated in Fig. 1. Excepting Purpuricenus budensis, for Purpuricenus desfontainii inhumeralis, Clytus rhamni, Plagionotus floralis, and Dorcadion triste phrygicum this is the first report on chromosome number.
To our knowledge, the chromosome number for Purpuricenus desfontainii inhumeralis is reported here for the first time. For Purpuricenus budensis this is the second determination of chromosome number. Our figures show Purpuricenus desfontainii inhumeralis and Purpuricenus budensis males as 2n=28 with a sex determining mechanism of Xy p . Of the three Purpuricenus species previously reported, Purpuricenus indus has the same number of autosomal pairs with an identical sex determining mechanism (SMITH & VIRKKI 1978). The haploid chromosome number (n) in Purpuricenus spectabilis was found to be 14, in which sex chromosomes have not been identified (EHARA 1956). OKUTANER (2011) counted 2n = 22 in Purpuricenus budensis from Turkey and this result is not in agreement with our record. This may be due to a counting error.
In Dorcadion triste phrygicum, chromosome number was 2n=24 (11 + Xy p ) with this being the first report on the chromosomes of this subspecies. The four taxa of the genus Dorcadion investigated previously for their chromosomes are Dorcadion anatolicum Pic, 1900, Dorcadion axillare moldavicum Dascãlu &  ASLANTAS 2018). It is too early to say that there is variation in the diploid chromosome numbers of the species of the genus Dorcadion and thus, more chromosomal data may provide useful clues.
Evidently the cerambycids are a large but cytogenetically little-known group of beetles for Turkish fauna. Therefore, more studies are needed to have an exhaustive knowledge of the number and morphology of chromosomes in Turkish species of Cerambycidae.