Trimerina microchaeta Hendel 1932: 11

= Trimerina indistincta Krivosheina 2004: 631 (syn. nov.)

Widespread in Europe; also occurs in the Russian Far East (Kamchatka) (Zatwarnicki 2013).

After examination of primary types of Trimerina microchaeta Hendel and T. indistincta Krivosheina we suggest to synonymize these two species. Krivosheina (2004) provided three characters to separate T. indistincta from T. microchaeta: a gena-to-eye ratio of 0.17 (versus 0.20 for T. microchaeta), yellow mid and hind coxae (versus all coxae partially dark), mid and hind tibiae entirely yellow (versus mid and hind tibiae with a dark band). These characters separating the two species are not consistent and fall within the variation range of T. microchaeta. Both nominal taxa have essentially the same male terminalia with characteristic postgonostyli (=postsurstyli) bearing short and apically rounded antero-ventral processes as illustrated for T. indistincta by Krivosheina (2004).

The holotype of Trimerina indistincta is shown in Fig. 1a.

a

b

c

d

Figure 1.

Ephydrid species from Finland. Scale bar = 1.0 mm.

a: Trimerina microchaeta. Holotype of Trimerina indistincta Krivosheina (specimen http://id.luomus.fi/GV.4020)  
b: Hydrellia mutata (http://id.luomus.fi/GV.16611)  
c: Ditrichophora calceata (http://id.luomus.fi/GV.16561)  
d: Pelina norvegica (http://id.luomus.fi/GV.19162)  

Best identified by structures of the male genitalia as figured by Collin (1966) and Canzoneri and Meneghini (1983).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Widespread in Europe; also known from North Africa and Pakistan (Zatwarnicki 1988, Zatwarnicki 2013).

Larvae of this species feed on pondweeds (Potamogeton) (Zatwarnicki 1988), the common frogbit (Hydrocharis morsus-ranae) (Hering 1926), and possibly also on water plantains (Alisma plantago-aquatica) (see Deonier 1971).

Best identified by structures of the male genitalia as illustrated by Collin (1966).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Central and Western Europe (Zatwarnicki 2013). The Finnish records are the first from Northern Europe.

Reared from water soldiers (Stratiotes), Potamogeton (Fischer 1997), and water starworts (Callitriche) (Hering 1957). Older, less reliable host records mention Hydrocharis as an additional host (see Deonier 1971).

Previously misidentified as Hydrellia flavicornis (Fallén, 1823) in Finland (Hackman 1980).

Best identified by structures of the male genitalia as illustrated by Collin (1966).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Widespread in Europe, it is recorded also from the Russian Far East (Zatwarnicki 2013).

No reliable records of the host plant of this species could be found.

Previously misidentified as Hydrellia chrysostoma (Meigen, 1830) (sensu Becker 1896) in Finland (Hackman 1980).

Best identified by structures of the male genitalia as illustrated by Collin (1966) and Canzoneri and Meneghini (1983) under the name Hydrellia flaviceps (auct. nec Meigen).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Widespread in Europe and probably across the Palaearctic Region, but poorly known (Zatwarnicki 2013).

Best identified by structures of the male genitalia as illustrated by Collin (1966).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Northern, Western and Central Europe (Zatwarnicki 2013).

Larvae have recently been found feeding on Alisma (Robbins 1990) and Stratiotes, possibly also Lemna and Alisma (see Deonier 1971).

Correctly identified by Richard Frey and Lauri Tiensuu but the record was never published. Specimen http://id.luomus.fi/GV.16611 is illustrated in Fig. 1b.

Best identified by structures of the male genitalia as illustrated by Collin (1966) and Canzoneri and Meneghini (1983).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Widely distributed in Europe and North Africa (Zatwarnicki 2013).

Larval host plant(s) unknown.

Best identified by structures of the male genitalia as illustrated by Collin (1966).

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Western and Central Europe, also recorded from Bulgaria (Zatwarnicki 2013).

The Finnish specimen was caught on water soldiers (Stratiotes), which is a host plant of H. tarsata (Przhiboro 2004).

Three most likely conspecific females were caught together with the male.

First recorded from Finland by Zatwarnicki and Kahanpää (2014). Holarctic, widespread in Europe (Zatwarnicki 2013).

All old records of Allotrichoma laterale (Loew, 1860) from Finland are misidentifications of Allotrichoma bezzii Becker, 1896.

First recorded from Finland by Zatwarnicki and Kahanpää (2014). A West-Palaearctic species found in almost all European countries and also in North Africa (Zatwarnicki 2013).

Specimen http://id.luomus.fi/GV.16561 is shown in Fig. 1c.

Two of the North European Hecamedoides species can be identified by the number of short, blunt anteroventral spine-like setae on the fore femur: one in H. unispinosus, several in H. glaucellus (Stenhammar, 1844). Hecamedoides kelmorum Stuke, 2011, a species recently described from Germany, also has a black antenna and a single anteroventral spine (Stuke 2011). Hecamedoides unispinosus and H. kelmorum are best identified by structures of the male genitalia. Two Finnish males (http://id.luomus.fi/GV.19243 and http://id.luomus.fi/GV.19235) were dissected to confirm their identification. The gonite of these specimens is clearly of the H. unispinosus type.

A Holarctic species. Recorded from Finland by Kahanpää 2013. New for Russia.

Hecamedoides unispinosus is much more common in Finland than H. glaucellus. The Fennica collection of MZH has only three specimens of the latter species: http://id.luomus.fi/GV.19146 from Turku (see Fig. 2b) and two specimens from Terijoki (=Russia, Leningrad Oblast, Zelenogorsk).

a

b

Figure 2.

Hecamedoides species from Finland. Scale bar = 1.0 mm.

a: Hecamedoides glaucellus (specimen http://id.luomus.fi/GV.19146)  
b: Hecamedoides unispinosus (specimen http://id.luomus.fi/GV.19147)  

Previously recorded from Norway, Germany and Slovakia (Zatwarnicki 2013). New for Russia.

Specimen http://id.luomus.fi/GV.19162 of Pelina norvegica is shown in Fig. 1d.