Denopelopia amicitia, a new Tanypodinae from Brazil (Diptera, Chironomidae)

Abstract A new species of Denopelopia from Brazil is described based on adult male and pupa. The male of the new species can be distinguished from all other species of the genus by the genitalia and fore-tibial spur morphology. The pupa is very similar to those of Denopelopia atria, but it can be distinguished by the absence of distinct constrictions in the respiratory atrium of the thoracic horn. Generic diagnosis to male and pupa of Denopelopia is emended and keys to male and pupae of known species are provided.


Introduction
The tanypod genus Denopelopia was erected by Roback and Rutter (1988) based on a single species (D. atria) from the Nearctic region. According to these authors, Denopelopia is closely related to Telmatopelopia Fittkau and Zavrelimyia Fittkau, these suppositions were recently corroborated by .
After the genus description, one undescribed species was reported from Panama based on adult male (Spies and Reiss 1996). So far, Denopelopia is composed of five described species, three of them with Asian distribution; Cheng and Wang (2005) described D. diaoluonica, D. bractea and D. viridula, from China, Kobayashi and Endo (2008) transferred Yaequintus irioquereus Sasa & Suzuki to the genus Denopelopia as senior synonym of D. bractea. The last species described on the genus, D. moema, was collected in Midwestern Brazil (Silva et al. 2014). Only one species, D. atria, has immature stages described, the remaining are known only as adult males.
In the present study, a new species from the Brazilian Amazon rainforest is described based on adult male and pupa, the generic diagnosis to male and pupa of Denopelopia (Roback andRutter 1988, Murray andFittkau 1989) is emended and keys to males and pupae are provided.

Materials and methods
A pupa was collected in a small pond using a hand net. It was reared in laboratory isolated in a vial to obtain the associated adult; for further details on rearing techniques see Mendes (2002). The material examined was slide-mounted in Euparal, following the procedures outlined by Pinder (1986Pinder ( , 1989). The colour is described as observed in specimen conserved in alcohol. The general terminology follows Saether (1980). The holotype of the named species was deposited in the Invertebrates collections of the Instituto Nacional de Pesquisas da Amazônia (INPA), Amazonas, Manaus, Brazil.

Denopelopia Roback & Rutter, 1988
Denopelopia Roback & Rutter, 1988: 117. Type species. Denopelopia atria Roback & Rutter, 1988. Emended diagnosis. Based on the additional characters found in D. amicitia sp. n., the generic diagnosis for the pupa and male of Denopelopia given by Roback and Rutter (1988) and Murray and Fittkau (1989) must be emended. Male: scutal tubercle absent; wing densely covered with macrotrichia, costa not produced beyond R 4+5 , ending clearly before M 1+2 ; tibial spurs with elongate apical tooth, more than half the length of the entire spur; tergite IX straight or rounded, with a transverse row of setae; gonocoxite with or without internal lobe. Pupa: wholly brown; thoracic horn elongated, with an apical nipple, a small plastron plate and respiratory atrium with or without constrictions; thoracic comb present; TVII with 3 lateral filaments; anal lobe with spines on the outer margin only; genital sac not surpassing apex of anal lobe. Diagnosis. Male: AR 1.92; wing with well-developed anal lobe; spur of the fore tibia with the most basal tooth longer and slender than the other lateral teeth and strongly curved backwards; tergite IX rounded; gonocoxite with a well-developed setose lobe at the base. Pupa: with a distinct apical nipple, 38 µm long and 42 µm wide, L/W 0.9; absence of distinct constrictions in the respiratory atrium of the thoracic horn.
Etymology. From Latin, amicitia, meaning friends, referring to friends who helped during fieldwork.
General coloration brown. Head yellow, occipital area brown; maxillary palp yellow; pedicel yellow, brown near the insertion of the flagellum; flagellomere I-XII light brown, VIII-VIV yellow. Thorax dark brown, pleura light brown. Legs yellow. Wings with membrane transparent, veins yellow. Abdomen: T I yellow, with light brown pigmentation on the anterolateral margin, T II-III yellow with clear brown band close to anterior margin; TIV with 1/3 anterior brown; TV-VIII brown, genitalia yellow.
Head ( Legs. Fore leg: tibia with an apical, pectinate spur, 47 µm long, with three lateral teeth and one elongate apical tooth, the most basal tooth is longer and slender than the other lateral teeth and strongly curved backwards (Fig. 2B); two preapical setae 138 µm long; width at apex of tibia 40 µm; ta 1 with one preapical stout setae, 86 µm long; ta 2 with one preapical stout setae, 75 µm long; ta 3 with two preapical stout setae, 72 µm long. Mid leg: tibia with two apical, pectinate spurs, 33 and 59 µm long, longest spur with three lateral teeth and one elongate apical tooth, shortest spur with three lateral teeth and one apical tooth (Fig. 2C); two preapical setae 119 µm long; width at apex of tibia 38 µm; ta 1 with a preapical stout setae, 71 µm long; ta 2 with two preapical stout setae, 65 µm long; ta 3 with two preapical stout setae, 48 µm long. Hind leg: tibia with two apical, pectinate spurs, 39 and 78 µm long, longest spur with three lateral teeth and one elongate apical tooth, shortest spur with three lateral teeth and one apical tooth (Fig. 2D); one preapical setae 182 µm long; width at apex of tibia 44 µm; ta 1 with one preapical stout setae, 90 µm long; ta 2 with two preapical stout setae, 61 µm long. Tibial comb on hind leg with 7 bristles, the lateral longer than the medial ones (Fig. 2E). Claws of all legs normal, curved, sharply pointed; pulvilli absent. Lengths (in µm) and proportions of leg segments as in Table 1.
Abdomen (Fig. 3C). Tergite I without shagreen, T II-TVIII with shagreen composed by scattered fine spinules. Sternite II with a large field of shagreen composed by spinules arranged in combs (Fig. 4D). T I with a distinct and elongate scar, 170 µm long. T VII with 3 lateral filaments, 252 µm long; filaments placed at 132, 210 and 275 µm from base to apex of segment. T VIII with 5 lateral filaments, 372 µm long. Anal lobe as in figures 3D and 4E, 350 µm long, 213 µm wide at base and with two lateral macrosetae with sticky sheaths; outer margins with 12 spinules; inner margins without spinules. Genital sac smaller than anal lobe, 233 µm long, 162 µm wide at base. GS/AL 0.67.

Systematic remarks
To date, Labrundinia is the only genus in the Tanypodinae which features a rounded male tergite IX, considered a synapomorphy for the group . The presence of this trait in D. amicitia n. sp. might suggest that a new genus should be erected to accommodate this species. However, considering that many tanypod genera are not properly studied, with only few described species, in many of these descriptions, this trait might have been overlooked by peers. Moreover, the pupa of D. amicitia sp. n. is very similar to that of D. atria, which leaves no doubt that the two species are congeneric. The adults of Denopelopia can be easily distinguished from those of Labrundinia by morphology of tibial spurs. In Denopelopia the spurs are well-developed with an elongated apical tooth and two spurs are present in the posterior tibia, while in Labrundinia the spurs are small, with subequal teeth and are absent in the posterior tibia. According to Roback and Rutter (1988), Denopelopia is closely related to Telmatopelopia and Zavrelimyia based on the overall morphology of adults and immature stages. However, adults of Denopelopia possess costa (C) not produced beyond R 4+5 and ending clearly before M 1+2 , while in Telmatopelopia and Zavrelimyia costa is slightly produced and ends above or slightly beyond M 1+2 . The pupae of Denopelopia has anal macrosetae with adhesive sheath and spines only at the outer margin of the  anal lobe, which contrast to Telmatopelopia with no adhesive sheath and Zavrelimyia that possesses spines both in the outer and inner margins of the anal lobe. In addition, Denopelopia has spines restricted to the base of the external membrane of the thoracic horn and possesses three lateral filaments in tergite VII, in contrast to Telmatopelopia and Zavrelimyia, which have the external membranes of the thoracic horn covered with spines and possess four lateral filaments in tergite VII. The larva of Denopelopia can be recognized by the presence of a trifid paraligula and elongated labial vesicles, in contrast to Telmatopelopia and Zavrelimyia where the paraligula is bifid and the labial vesicles are more or less rounded.
The male of D. amicitia sp. n. can be distinguished from all other species of the genus by the hypopygium morphology. It has a well-developed setose lobe at the base of the gonocoxite, which is absent or reduced in other species of the genus. In addition, the male of D. amicitia sp. n. has the anal lobe of the wing well-developed, which sets it apart from D. viridula and D. diaoluonica, that have it reduced and absent, respectively; the absence of two scale-shaped bristles at the apex of the anterior tibia, the well-developed anal lobe of the wing and the sternapodeme with a pointed anterior process, distinguishes D. amicitia sp. n. from D. irioquerea; the morphology of the anterior tibial spur and the rounded tergite IX distinguishes D. amicitia sp. n. from D. moema and D. atria. The pupal stage is similar to that of D. atria due to the morphology of the thoracic horn and the number of lateral filaments on tergite VII, but can be distinguished by the absence of distinct constrictions in the respiratory atrium and by the low length/width ratio of the apical nipple.

Ecological notes
There is little information on the biology of Denopelopia, since only D. atria has its immature stages described. This species was described based on material collected and reared from a shallow drainage ditch amongst Typha sp., with low dissolved oxygen and relatively high iron concentrations (Roback and Rutter 1988) in Florida (USA). This species has also been collected in lentic environments in Costa Rica (Epler 2001) and an unreared larva of the genus was recorded from Southeastern Brazil by Trivinho-Strixino and Strixino (1995).
The pupa of D. amicitia sp. n. was collected in a small disabled pisciculture pond, associated with marginal vegetation, in a eutrophic environment where a carcass of a large animal, in advanced stages of decomposition, was observed.
Several attempts to collect additional material were made; however, the pond where it was collected was drained and sampling in the adjacent areas, such as streams and wetlands, was not successful.