DISCOVERY OF EPIZOIC ALGAE ON SEMIAQUATIC WEEVILS BAGOUS TUBULUS CALDARA ET O’BRIEN, 1994 (COLEOPTERA: CURCULIONIDAE) IN EUROPE

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Yunakov N. N. Natural History Museum University of Oslo, Norway, e-mail: n.yunakov@gmail.com, ORCID: 0000-0002-0824-7804 Khrapov D. D. Ukrainian Entomological Society, Lviv, Ukraine, e-mail: denys.khrapov@gmail.com, ORCID: 0000-0002-9868-1435 ––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Received 25.11.2020 Accepted 15.12.2020 by Dr. Yu. A. Guglya Published 21.12.2020 UDC 595.768.23:582.232:582.263:591.557(477.23) DOI: 10.36016/KhESG-2020-28-2-3

Small-and medium-sized green spots are constrained to the dorsal and lateral surfaces of pronotum, elytra, and femora of beetles. We assume that succidations, microstructure of scales along with semiaquatic way of life provides optimal substrate for growth of algal mats. It is still unclear how algal mats affect beetle life or properties of scales and coating. Taxonomic composition of those mats is unknown yet. According to available data on epizoic organisms, we presume that it may be the species of Ulvophyceae, Chlorophyceae, and/or Cyanobacteria. 1 fig., 17 refs. Key words: algal mats, epizoic flora, symbiosis, commensalism, beetles, Chlorophyta. Epizoic communities of green algae and cyanobacteria on vertebrates and terrestrial arthropods are forming mats. All known terrestrial epizoic algae are restricted to Ulvophyceae and Chlorophyceae, the phylogenetically related classes of Chlorophyta (Leliaert et al., 2016).
Mats formed by monospecific or compound multispecific communities of algae. Sometimes algae co-occur with various species of Cyanobacteria. In some cases, algal and cyanobacterial mats provide a substrate for further growth of liverworts (Machado, Vital, 2001) and some other bryophytes (Gradstein, Vitt, Anderson, 1984), later multilevel communities constrained to mountain rainforests of Papua New Guinea, Madagascar, and Tropical America.
Ve r t e b r a t e s . Mammals. Molecular study of hair symbionts taken from six sloth species in Costa Rica and Panama revealed the diversity of algae comprising three co-occurrence patterns: non-specific terrestrial genera and stenotopic algal genera which includes the remarkable Trichophilus restricted to cloth hairs (Suutari et al., 2010).

A r t h r o p o d s . O p i l i o n e s .
A remarkable case of co-occurrence epizoic cyanobacteria and liverworts on harvestmen has been documented in Brazil (Machado, Vital, 2001). Harvestmen with living cyanobacteria are known from Trinidad (Young, Moore, Townsend, 2018).

D i p l o p o d a .
Martínez-Torres, Flórez Daza, and Linares-Castillo (2011) described co-occurrence of platyrhacid millipedes with ten epizoic bryophyte species in Colombia.
C o l e o p t e r a . A number of cases of growing algae on beetles are noted frequently by entomologists throughout the tropical regions, e.g., Geobyrsa nodifera Pascoe, 1872 from Panama (Jolivet, 1998). Species of Tenebrionidae, Anthribidae, Brentidae, and Curculionidae (e.g., Holonychus Schoenherr, 1840 and Lithinus Klug, 1833) bearing algae were observed by macro-photographer Paul Bertner in Madagascar (https://rainforests. smugmug.com). Comprehensive study of epizoic organisms associated with weevils of the genus Gymnopholus has been done in Papua New Guinea (Gressitt, Sedlacek, 1967, 1970Gressitt, 1966aGressitt, , 1966bGressitt, , 1977Gressitt, Samuelson, Vitt, 1968) and recently confirmed by Riedel and Kilmaskossu (2017). Communities are forming a compound pattern of co-occurrence of bryophytes, lichens, and mites. Gressitt assumes such coexistence provides benefits to weevils, e.g., camouflage properties, hence, beetles might stimulate the growth of those organisms via body succidations and specific pitted microsculpture of the body surface.
No evidence of epizoic plants on weevils is reported yet from Europe.

M a t e r i a l s a n d m e t h o d s .
Beetles were collected by sweeping flooded grasses in shallow mineral springs (depth ca. 30-40 cm). Water from these springs is enriched with flammable natural gas. Four specimens are preserved for further algological and molecular study. Sampling   During examination of Bagous tubulus series collected in Lviv Region of Ukraine the epizoic green algae were detected. 23 of 24 specimens bear algal mats. Small-and medium-sized green spots are constrained to the dorsal and lateral surfaces of pronotum, elytra, and femora of beetles (Fig. 1). Bagous species have granulate, moderately to strongly pitted non-hydrofuge scales with clear and shellac-like or dense and subopaque waterproof coating, later often concealing scales and cuticle (O'Brien, Askevold, 1992).
We assume that such coating along with a semiaquatic way of life provides an optimal substrate for the growth of algal mats. It is still unclear how algal mats affect beetle life or properties of scales and coating. Taxonomic composition of those mats is a subject of further study. We presume that it may be the species of Ulvophyceae, Chlorophyceae, and/or Cyanobacteria.