The flightless marine midge Pontomyia (Diptera: Chironomidae): ecology, distribution, and molecular phylogeny

Abstract

Pontomyia Edwards, 1926 (Diptera: Chironomidae) is a genus of exclusively marine flightless midges. There are four described species from the Indo-Pacific, and one undescribed species known only from females, pupal skins, and larvae from the Atlantic/Caribbean. They are poorly known owing to their small size (~1.0 mm), extremely short adult life (< 3 h), and unusual habitat for an insect (coastal lagoons, bays, or rock pools). We reviewed scattered literature on their biology and systematics, presented photomicrographs of the male hypogium, and updated the geographic distribution of each species. We carried out the first molecular study to elucidate relationships among and within three of the species. Results from our four-gene phylogenetic reconstruction using combined gene tree and species tree approaches showed that Pontomyia natans, Pontomyia oceana, and Pontomyia pacifica are each well-supported clades, with P. natans as sister to P. oceana + P. pacifica. Genetic distances based on mitochondrial cytochrome oxidase I are extraordinarily large within P. natans and P. pacifica, which suggests that they may be cryptic species complexes.z oj_680 443..456

A new surface gliding species of Chironomidae: An independent invasion of marine environments and its evolutionary implications

“…The degree of adaptation varies among these groups. The Chironominae Pontomyia is arguably best known for its specialized marine lifestyle (Cheng & Collins, ; Huang & Cheng, ), skating on the water surface as males, with shortened oar‐like wings, elongated halteres, strongly elongated forelegs, shortened and robust middle and hind legs, and a fully and permanently rotated hypopygium. Even though D. sinicus sp.…”

The Afro–Oriental Genus Yaeprimus Sasa et Suzuki (Diptera: Chironomidae: Chironomini): Phylogeny, New Species and Expanded Diagnoses

“…The divergence is distinct yet can be also observed in other genera as well. For example, Pontomyia Edwards also contain two kinds of gonostylus, reduced in P. oceana Tokunaga, while, normal in other two species [36]. More examples can also be found in Chironomus (C. crassiforceps Kieffer) [10], Polypedilum (P. minimus Lin et al) [37], Riethia (R. phengari Cranston) [16], Sticotochironomus (S. crassiforceps Kieffer) [10] and Orthocladius v. d. Wulp (O. brevistylus Yamamoto, Yamamoto et Tang) [38].…”

“…Fore tibia with a conical scale bearing a slender, distal-hooked spur, 25-30 (2) µm long. Mid tibia with two separated combs, one bearing a distal-hooked spur, [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]28 (3) µm long, another comb with even comb teeth, unspurred; hind tibia with two separated combs, the small one bearing a distal-hooked spur, 25-40, 35 µm Hypopygium ( Figures 4H and 6A,B). T IX with a row of 4-6 setae, arising from fairly large microtrichia-free pit, without distinct lateral group.…”

Ecological and Societal Services of Aquatic Diptera

“…Numerous species in several families (e.g., Coelopidae and Helcomyzidae) are associated with seaweed (Figure 2d), and their life cycles are coordinated with tidal rhythms [29]. Diptera are perhaps the only insects that have entered the open ocean beneath its surface, with the chironomid Pontomyia among the most unusual [30,31,32]. These and a few other chironomids, such as the epibionts on marine turtle carapaces, are truly submarine [33]; other chironomid species also probably live in the open ocean [34].…”