Myrmecophilus acervorum

Myrmecophilus acervorum (Panzer, 1799) Specimens examined. — LATVIA • 1 ♀ (Fig. 1 A, B); Rīga, Bolderāja; 57°01'20"N, 24°01'06"E, altitude ~ 3 m a. s. l.; 19 May 2022; Aleksandrs Balodis leg.; xerothermic riverside, between River Buļļupe and Lielā Street north of Jaunie Bolderājas kapi cemetery; individual released after observation • 1 ♀, juv. (total body length: 1.47 mm, Fig. 1 C, D); Rīga, Jugla, Strazdumuižas Street; 56°59'00"N, 24°15'32"E, ~ 4 m a. s. l.; 13 June 2024; Aleksandrs Balodis leg.; Lake Juglas sloping, semi-open shore (Fig. 1 E, F); LNDM. For localities in the WGS 84 coordinate system, please refer to Suppl. material 1. The observation near River Buļļupe comes from a mixed forest stand on sandy soil, in xerothermic conditions, with low grassy vegetation. The discussed specimen was observed on a fallen trunk of a birch tree, Betula pendula, cut about one year before (in 2021) and, along with other birch trunks, deposited (piled) about six months prior to the observation ~ 50 m from the riverside. The specimen was observed on the upper side of a trunk within a group of black Lasius sp. ants. The observation at Juglas lakeside is from a partially open and moderately wet sloping edge of a lake with deciduous trees and bushes, at an east-exposed bank of the lake. The specimen was observed on black soil in a small group of black garden ants Lasius niger (Linnaeus, 1758). Both localities are subjects of seasonal floods and water level fluctuation in the River Buļļupe and Lake Juglas, respectively. The straight-line distance between the localities is about 15.2 km. Biogeographically, the Latvian records belong to the Boreal Region. The highest proportion of available records of M. acervorum come from the Continental Region followed by the Atlantic Region (Fig. 2). When compared to the previously known distribution (GBIF 2024), the Latvian contribution to the European regional EOO is 129 743 km 2 and to the AOO is 8 km 2.