Linnaemya bergstroemi Pohjoismäki & Haarto, 2015, n. sp.
Creators: name: Pohjoismäki, Jaakko
name: Haarto, Antti
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Tachinidae
Linnaemya
Linnaemya bergstroemi

description: Distinction of Linnaemya bergstroemi n. sp. from the other species of Linnaemya
Although Linnaemya bergstroemi n. sp. is an unusual representative of the genus in the Palaearctic, four similarly dark species with irregular discal abdominal setae, Linnaemya anthracina (Figs 2, 7, 13–14, 23–24, 34, 36, 42, 43), L. varia (Figs 3, 8, 15–16, 25–26, 32, 37, 44), L. nigrescens (Figs 4, 9, 17–18, 27–28, 38, 45) and L. tessellata (Figs 5, 10, 19–20, 29–30, 39, 46), are known from the northern parts of North America. While these species have all been assigned to the subgenus Ophina Robineau-Desvoidy, L. anthracina differs considerably from the remaining three by its external characters. For example, L. nigrescens, L. tessellata and L. varia have prementum shorter than eye height, always 3+3 acrostichal setae, epandrium high, in lateral view more prominent than the surstylus, surstylus slender, truncate and shorter than syncercus, whereas L. anthracina (and L. bergstroemi n. sp.) has prementum longer than eye height, 3+1–3 acrostichal setae, epandrium flat, almost as high as surstylus, surstylus broad, pointed and longer than syncercus. The male L. anthracina specimen at BIO was originally misidentified as L. varia, as it has 3 post-sutural acrostichal setae on the thorax instead of 1 (see diagnosis in Brooks 1944). This confusion is also explained by the fact that L. anthracina, L. bergstroemi n. sp. and L. varia all have 3 dorsal preapical setae on all tibiae and commonly 4 katepisternal setae, character states not known in any other Linnaemya (Brooks 1944; van Emden 1960; Mesnil 1971; Shima 1986). There are only two male L. anthracina specimens in CNC, one of which was examined from high resolution images to confirm the identity of the BIO specimen. The specimens are identical except for the CNC male having only 1 post-sutural acrostichal seta as indicated by Brooks (1944).
Despite their similarity, L. anthracina and L. bergstroemi n. sp. can be readily differentiated by a number of characters. The first flagellomere, which in both sexes of L. bergstroemi n. sp. is broad and rectangular (Figs 11, 21), is more elongated and rounded in L. anthracina (Figs 13, 23). Furthermore, the first flagellomere of L. bergstroemi n. sp. is scarcely longer than the pedicel while it is twice as long in L. anthracina. The male of L. bergstroemi n. sp. has a strong outer vertical seta, which is weaker, although present, in L. anthracina. The prementum in L. bergstroemi n. sp. is narrow and elongated, longer than the face in both sexes (Figs 1, 6), but is distinctly wider and shorter than the face in L. anthracina (Figs 2, 7). The female abdominal chaetotaxy in L. anthracina is markedly sparser than in L. bergstroemi n. sp., like for example the single pair of discal setae on tergite 4. This, however, might not be a stable feature, as chaetotaxy varies also between specimens of L. bergstroemi n. sp. In the female of L. anthracina the parafacial is covered with dense, silvery microtomentum and the wing veins are infuscated. The medial cleft of sternite 5 in L. bergstroemi n. sp. is U-shaped, whereas in L. anthracina it is V-shaped (Figs 33–34). Other differences in the male genitalia are surprisingly small, the greatest being the shape of the dorsal part of the distiphallus and the relative length of the pregonites (Figs 41–42), which are 1.7 times as long as their narrowest point in L. bergstroemi n. sp. compared to 3.0 times as long in L. anthracina. The basiphallus is also more rounded and distinctly wider in lateral view in L. bergstroemi n. sp.: 3.0 times as long as its narrowest point as opposed to 4.3 in L. anthracina (Figs 41–43). The presence of a sclerotized ridge on the distiphallus separates L. anthracina and L. bergstroemi n. sp. from all the other members of the subgenus Ophina analyzed in this study (Figs 44–48). However, a similar feature is present in L. tessellans of the subgenus Bonellimyia Townsend (Fig. 49).
Linnaemya varia is readily distinguished from all the other Linnaemya species included in this study by its broad frons, which is wider than the eye width in both sexes (Figs 16, 26). Besides the color of the epistomeyellow in L. nigrescens —males of L. nigrescens and L. tessellata differ by the shape of the antenna, the first flagellomere of L. nigrescens being broadly rectangular (Fig. 17) compared to cylindrical in L. tessellata (Fig. 19). Additionally, the surstylus of L. tessellata is strikingly wide at its base (Fig. 39) and the gonites are distinctive in all three species (Figs 44–46). While L. nigrescens and L. tessellata males are easily identifiable, we are not confident in differentiating the females based on the material at hand. Based on this material, the two species also have an overlapping distribution in North America.
In the CoI sequence similarity analysis (Fig. 55; Tab. 1), L. bergstroemi ’s closest match is L. anthracina, these two species being separated from each other by about a 1% sequence difference. Similar poor separation by CoI is evident also in L. nigrescens – rossica – tessellata – varia and some other Tachininae with a boreoalpine-arctic distribution, such as Peleteria aenea (Staeger), P. prompta (Meigen) and P. rubescens (Robineau-Desvoidy), as well as Nowickia alpina (Zetterstedt) and N. marklini (Zetterstedt) (Fig. 55). As a note, the CoI tree does not represent a true phylogeny but helps to illustrate differences between taxa. For example, in our analyses Nowickia Wachtl is embedded within Tachina Meigen, whereas 12S and 16S sequences combined with morphological data place them as sister genera (Novotná et al. 2009).
CoI is known not to work well in separating species in other brachyceran taxa and this could be due to a number of reasons (Whitworth et al. 2007; Haarto & Ståhls 2014). Despite this shortcoming, the CoI comparison suggests that L. bergstroemi n. sp. and L. anthracina do not show any affinity to the known species in the subgenus Ophina. The same is suggested by features of the male genitalia, such as the size and shape of sternite 5 and epandrium, and the prominent sclerotized ridge on the distiphallus (Figs 44–49). Although L. bergstroemi n. sp. and L. anthracina seem to share features with L. tessellans of the subgenus Bonellimyia, a more detailed phylogenetic analysis will be needed to solve their correct placement.
description: Published as part of Pohjoismäki, Jaakko & Haarto, Antti, 2015, Linnaemya bergstroemi n. sp. (Diptera: Tachinidae) — a new parasitoid fly from the Finnish Lapland, pp. 581-597 in Zootaxa 4059 (3) on pages 593-595, DOI: 10.11646/zootaxa.4059.3.9, http://zenodo.org/record/244767