Pytho depressus (Linnaeus, 1767)

Jaskula, Radomir, Coso, Denis, Tamutis, Vytautas & Ferenca, Romas, 2024, Updated distributional checklist of the genus Pytho Latreille, 1796 of the Palearctic realm with the first records of P. abieticola J. R. Sahlberg, 1875 from Lithuania and the family Pythidae (Coleoptera) from Moldova and Serbia, Biodiversity Data Journal 12, pp. 115422-115422 : 115422

Pytho depressus (Linnaeus, 1767)

Materials

Type status: Other material. Occurrence: recordedBy: col. local collector; occurrenceID: CA3E8475-ED52-5CE4-9FB1-5CAD1DAA4799; Location: country: Moldova; municipality: Municipality of Chișinău; locality: Chișinău : Rose Valley Park ; verbatimCoordinates: N47.002119 E28.852038; Identification : identifiedBy: Radomir Jaskula ; Event : eventDate: 18.12.2019.; Record Level: type: 3 specimens; collectionID: RJC; collectionCode: RJC/P005; RJC/P006; RJC/P007 Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: 77F8868F-715A-58B5-9300-DCBA72D33244; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.705656 E20.522934; Identification : identifiedBy: Enrico Ruzzier ; Event : eventTime: 28.01.2018.; fieldNotes: under bark of dead pine; Record Level: type: 1 specimen (photographed by Denis Ćoso) Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: 965E1100-F89E-586E-99FE-DBE34EB2D519; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.705656 E20.522934; Identification : identifiedBy: Denis Coso ; Event : eventDate: 06.02.2018.; fieldNotes: under bark of dead pine; Record Level: type: 1 specimen (photographed by Denis Ćoso) Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: 83F31E9D-B988-504B-8775-3F6260A2B3A2; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.705656 E20.522934; Identification : identifiedBy: Denis Coso ; Event : eventDate: 02.03.2018.; fieldNotes: under bark of dead pine; Record Level: type: 2 specimens (photographed by Denis Ćoso) Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: 84AF98F7-B5C7-5E3B-B981-A9A6E7A56646; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.706434 E20.523825; Identification : identifiedBy: Denis Coso ; Event : eventDate: 02.12.2018.; fieldNotes: under bark of dead pine; Record Level: type: 1 specimen (observed by Denis Ćoso) Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: 37383745-A505-561A-BC3B-5F519E817230; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.706434 E20.523825; Identification : identifiedBy: Denis Coso ; Event : eventDate: 27.01.2019.; fieldNotes: under bark of dead pine; Record Level: type: 1 specimen (observed by Denis Ćoso) Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: C89F44FA-9A39-5385-95D7-D0AA3152E65D; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.706434 E20.523825; Identification : identifiedBy: Denis Coso ; Event : eventDate: 09.02.2020.; fieldNotes: under bark of dead pine; Record Level: type: 1 specimen (observed by Denis Ćoso) Type status: Other material. Occurrence: recordedBy: Denis Ćoso; occurrenceID: 354BF2F3-2CF2-5BE6-A02E-93A8677AA082; Location : country: Serbia; stateProvince: City of Belgrade District; municipality: Municipality of Vozdovac ; locality: Beli Potok ; verbatimCoordinates: N44.706516 E20.524496; Identification : identifiedBy: Denis Coso ; Event : eventDate: 07.01.2021.; fieldNotes: under bark of dead pine; Record Level: type: 1 specimen (observed by Denis Ćoso); source: www.inaturalist.org/observations/174250744

Description

Relatively small beetles with strongly flattened bodies, body length (measured from anterior margin of clypeus to the end of elytra) of three studied specimens from Moldova (Serbian individuals photographed in the field were not measured): 7.86 mm, 10.64 mm and 12.13 mm. Pronotum widest in the middle, with sides not constricted anteriorly, clypeus 3.2 times wider than long. In examined specimens head, pronotum and elytra were brown-bluish, legs brown-black and antennae brown-yellow, with yellowish pale body.

Distribution

Palaearctic taxon. Like most members of the genus, P. depressus prefers cold boreal regions and are more sporadic outside such areas. Until now, it has been recorded from 32 countries, including the first records from Moldova (Fig. 4 ) and Serbia (Fig. 5 ) presented in this paper, making it the most widely distributed species amongst all Palaearctic Pytho (for details, see distributional checklist below). The occurrence of this species in central Italy ( Dias et al. 2021), from where its the southern-most record in Europe is known, should be confirmed by new data as it is possible that the material was mislabelled as this locality is placed outside the species' distribution ( Vázquez-Albalate 1993).

Ecology

Different literature sources (e.g. Pollock (1991), Miessen (1994), Siitonen and Saaristo (2000), Smith and Sears (2012), Kapla et al. (2021), Chittaro et al. (2023)) show that P. depressus occurs in forested areas from lowlands to mountains (up to 2200 m a.s.l.). Large host tree trunks are preferred, but occasionally wood pieces up to 6 cm in diameter are also accepted. Dead pines ( Pinus spp.), both fallen and standing trees, are selected by adults as places for development, but it has furthermore been noted on other dead conifers, such as spruce ( Picea spp.), fir ( Abies spp.) and larch ( Larix spp.) and, occasionally, even on deciduous tree species including birch ( Betula spp.), willow ( Salix spp.) and poplar ( Populus spp.). Moreover, Pollock (1991) mentioned that rarely P. depressus lives in still fresh trees with the bark still intact and without fungal activity. In eastern Fennoscandia, Ananyev et al. (2022) noted this species from a burnt area where its larvae were quite abundant under the bark of coniferous trees in fire-affected spruce forest.

Literature data suggest that a variety of food accepted by larvae of this species - from (mainly) rotting phloem and pulp, sawdust from the food of other insect larvae, their excrement and microorganisms living amongst the mentioned materials to (rarely) larvae of other saproxylic beetles ( Saalas 1917, Larsson 1945, Palm 1951, Kaszab 1969, Burakowski 1962, Anderson and Nilssen 1978, Smith and Sears 2012). The physiological anti-freezing adaptations observed in this species shows that it can survive freezing down to -27oC ( Zachariassen 1979, Lundheim and Zachariassen 1993).

Based on observations from Russian Karelia, Martikainen and Koponen (2001) suggest that Meteorus corax Marshall, 1898 ( Hymenoptera , Braconidae ) is a parasite of P. depressus larvae. In Ukraine, a tarsonemid mite Tarsonemus metacinops Kaliszewski, 1993 ( Acari, Tarsonemidae ) was recorded under the elytrae of P. depressus ( Khaustov and Magowski 2003).

Conservation

Cálix et al. (2018) listed Pytho depressus in the IUCN Red List of European Saproxylic Beetles as least concern (LC category), as it is the most widely distributed taxon amongst all Palaearctic species classified in the genus. On the other hand, it is necessary to note that the population trends of P. depressus are poorly studied. Moreover, in some regions or even countries, the species is rare or sporadic and often occurs in isolated populations (e.g. Benedikt 2011, Chittaro and Sanchez 2016, Háva and Zahradník 2021, Kapla et al. 2021, Thomaes et al. 2022) which potentially can be threatened in the future. Unsustainable forestry, especially logging and removal of large dead trees for economical, health and safety reasons, is recognised as one of the main threats for this saproxylic species even if it is known as a habitat generalist ( Laaksonen et al. 2008). Some populations of this species are protected in national parks and/or nature reserves, for example, in Switzerland ( Chittaro et al. 2023), Poland (e.g. Burakowski et al. 1987, Szafraniec 1997, Kubisz and Tsinkevich 2001, Kubisz 2004 Burakowski et al. (1987), Szafraniec (1997), Kubisz and Tsinkevich (2001), Kubisz (2004), Marczak 2020, Buchholz et al. 2021, Marczak et al. 2023), Belarus ( Lukin 2010), Bulgaria ( Kovács et al. 2011), China ( Painter et al. 2007), Russia (e.g. Painter et al. 2007, Alekseev 2014, Egorov et al. 2020, Ananyev et al. 2022, Ruchin et al. 2022), Finland ( Finnish Biodiversity Information Facility 2023b) and the United Kingdom ( Jaskuła - unpublished).

Biology

Pytho depressus , like all members of the genus, is a saproxylic species and its life cycle takes at least two years ( Burakowski 1976). Shortly after copulation, males die while females lay eggs in small clusters of several pieces under the bark of host trees in May-June. The sperm ultrastructure in this species was described by Dias et al. (2021). Embryonic development takes about two weeks. Larvae are elongated (reaching 22-30 mm) with body yellowish pale and live under loose bark ( Burakowski 1976, Iablokoff-Khnzorian 1985, Pollock 1991). Pupation usually takes place in August or September ( Burakowski 1976). Adults overwinter in pupal chambers; they can be characterised by a small body size (7.5 to 13.7 mm long) and a dorsoventrally flattened body well adapted for activity and movements in the cambial layer, a microhabitat also shared by larvae.

Figures

Figure 4. Distribution of Pytho depresus (Linnaeus, 1767) in Moldova.

Figure 5. Distribution of Pytho depressus (Linnaeus, 1767) in Serbia.