New species from well-studied taxa such as Sepsidae (Diptera) are rarely described from localities that have been extensively explored and one may think that New York City belongs to this category. Yet, a new species of Themira (Diptera: Sepsidae) was recently discovered which is currently only known to reside in two of New York City’s largest urban parks. Finding a new species of Themira in these parks was all the more surprising because the genus was revised in 1998 and is not particularly species-rich (13 species). Its status is confirmed as a new species based on morphology, DNA sequences, and reproductive isolation tests with a closely related species, and is described as Themira lohmanus Ang, sp. n. The species breeds on waterfowl dung and it is hypothesized that this makes the species rare in natural environments. However, it thrives in urban parks where the public feeds ducks and geese. The mating behavior of Themira lohmanus was recorded and is similar to the behavior of its closest relative T. biloba.
Keywords: cryptic species, Sepsidae, species description
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| Figure 2. Adult male (A–M), showing lateral (A) and dorsal (B) views of habitus, anterior (C) and ventral (D) views of head capsule, anterior and posterior views of fore leg (E), mid leg (F) and rear leg (G); ventral view of abdomen (H) showing modified 4th sternites; anterior (I), dorsal (J), left (K) and right (L) views of hypopygium, as well as various views of the penis (M). |
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| Figure 3. Adult female (A–H), showing lateral (A) and dorsal (B) views of habitus (sans abdomen), anterior (C) and ventral (D) views of head capsule, anterior and posterior views of fore leg (E), mid leg (F) and rear leg (G), and ventral view of abdomen (H). |
Themira lohmanus Ang, sp. n.
Diagnosis: Themira lohmanus is a relatively large, robust-looking sepsid species that resembles T. biloba. However, adult T. lohmanus males can be readily differentiated from the latter by their uniquely shaped, asymmetrical surstyli, which is symmetrical in T. biloba (Fig. 1A, see Morphological analysis section). While females of these two species do not have distinct structural differences, they can potentially be distinguished based on the color of the sclerous cuticle: in T. biloba, it tends to be glossy black while T. lohmanus tends to have a cupreous tinge. However, these characters may not be easily differentiated in faded specimens.
Etymology: The new species is named after David J. Lohman, for his generous contributions of specimens to sepsid taxonomy.
Distribution: Nearctic. Thus far only found in New York City (Central Park and Prospect Park); likely to be found in more localities in the future, especially where waterfowl congregate.
Yuchen Ang, Rudolf Meier, Kathy Feng-Yi Su and Gowri Rajaratnam. 2017. Hidden in the Urban Parks of New York City: Themira lohmanus, A New Species of Sepsidae Described Based on Morphology, DNA Sequences, Mating Behavior, and Reproductive Isolation (Sepsidae, Diptera). ZooKeys. 698; 95-111. DOI: 10.3897/zookeys.698.13411
