Description of fourth instar larva and pupa of Atrichopogon delpontei Cavalieri and Chiossone ( Diptera : Ceratopogonidae ) from Brazilian Amazonia

The fourth instar larva and pupa of Atrichopogon delpontei Cavalieri and Chiossone are described for the first time. The immatures were collected from stream margins in the northern Brazilian states Rondônia and Piauí, and subsequently reared to adults. Larvae and pupae are illustrated and photomicrographed. Details on the rearing process and feeding behavior in laboratory, bionomics and notes on habitats are also provided.


INTRODUCTION
The worldwide genus Atrichopogon Kieffer, one of the most speciose in the family Ceratopogonidae, includes species that are very similar in appearance and most of them cannot be confidently identified (Edwards 1926, Debenham 1973, Borkent and Picado 2004, Spinelli and Marino 2007).In contrast to this the immature stages are excellent for species recognition (Nielsen 1951, Ewen and Saunders 1958, Chan and Linley 1988, Szadziewski et al. 1995).Some live in moist, terrestrial habitats of decaying organic matter like dung or rotting wood, and others develop in aquatic and semiaquatic habitats (hygropetric) on partially submerged stones, rotting wood, algae or mosses along the margins of streams, ponds or lakes (Szadziewski et al. 1997).Borkent and Spinelli (2007) Ewen and Saunders (1958).PABLO I. MARINO et al.The purpose of this paper is to fully describe for the first time with modern standars, the fourth instar larva and pupa of A. delpontei from specimens recently collected in northern Brazil.

MATERIALS AND METHODS
Field work was conducted between 2011 and 2012 in the states of Rondônia and Piauí (Fig. 43).
Larvae and pupae were collected at river margins with a pair of tweezers.Larvae were preserved in ethanol 80% and pupae were kept alive isolated in 2 mm plastic vials, containing a piece of wet filter paper to maintain humidity.They were observed daily until adult emergence.After emergence adults were kept alive for 24 hours before being preserved to ensure their pigmentation was complete.They were subsequently stored in vials containing ethanol 80% with their respective exuviae.Larval and pupal exuviae and adults were slide mounted in Canada balsam following the technique described by Borkent and Spinelli (2007).Specimens were examined, measured and drawn using a binocular compound microscope.Illustrations were made with pen and ink using an attached camera lucida.Photographs were taken with a Micrometrics SE Premium digital camera, through a Nikon Eclipse E200 microscope.For scanning electron microscopy (SEM), larvae and pupae were prepared following the technique of Ronderos et al. (2000Ronderos et al. ( , 2008)).Photomicrographs were taken with JSM6360LV.

Atrichopogon (Lophomyidium) delpontei
Adult diagnosis.The only species of Atrichopogon (Lophomyidium) in the New World in which male have a six scutellar setae, the sternite 9 is deeply excavated and the distal margin of the aedeagus-parameral complex is pointed.Female have six scutellar setae, flagellomeres 9-13 elongate, palpus entirely brown, wing very hairy with more than 50 large macrotrichia in anal cell and small, unequal spermathecae with short necks.
Taxonomic discussion.Atrichopogon delpontei belongs to the subgenus Lophomyidium, as it was pointed out by Wirth (1994).The study of the holotype of A. delpontei deposited in the collection of the MLPA, reveals that it possesses six stout bristles on the scutellum instead of the four bristles mentioned by Cavalieri and Chiossone (1972) in the original description, as well as in the notes provided by Wirth (1994) in the revision of the Nearctic species of the subgenus.Therefore, considering that A. delpontei possesses six scutellar bristles, it should key out to couplet 4 in Wirth (1994) where it may be distinguished from Atrichopogon archboldi by the excavation of the male sternite 9 (deeply excavated in A. delpontei, slightly excavated in A. archboldi) and by the distal margin of the aedeagus-parameral complex (pointed in A. delpontei, rounded in A. archboldi).The female is almost indistinguishable from A. archboldi, except for the very hairy anal cell with more than 50 macrotrichia (28-35 in A. archboldi) and the spermathecae with short necks (without necks in A. archboldi).
The only description of larva and pupa of a species belonging to the subgenus Lophomyidium  Antenna (AN); dorsal comb (DC); lateral arms (LA).Head capsule chaetotaxy: j, collar pits; m, posterolateral pits; n, anterolateral pits; o, parahypostomal setae; p, posterior perifrontal setae; q, postfrontal seta; r, postnotal pits; t, prefrontal seta; u, mesolateral seta; v, posterolateral seta; w, anterolateral seta; x, paranntenal setae; y, ventral seta; z, frontal pits.   is the one provided by Ewen and Saunders (1958) for Atrichopogon fusculus, whose adults bear four scutellar bristles.It is very incomplete, and therefore it is very difficult to compare the immatures of A. fusculus with those of A. delpontei, herein described.However, the larvae of both species share a similar chaetotaxy of the head capsule, and the anal segment of the larvae of A. fusculus bears two pairs of long setae, but the posterolateral pair is stronger.The larva of A. delpontei possess scopae.and palatal bar, two structures that still were undescribed in any larvae of this genus, and the prothorax has a dorsal plate bearing two strong setae.
With regard to the pupa, Borkent (2014) mentioned for Atrichopogon that the fourth segment lacks lateral setae or bears a single one (L-1-IV), but A. delpontei clearly exhibits two lateral setae (L-2-IV and L-4-IV).Furthermore, the pupa of A. delpontei shows the following distinctive features: the dorsal apotome lacks a medial tubercle on its posterior margin, and the terminal process is short and directed laterally.
Bionomics.The larva of A. delpontei exhibits a toothed mandible without fossa mandibularis and hypognathous mouthparts, typical of herbivorous larvae whose feed diatoms, bacteria, fungi and other algae (Thomsen 1937, Hribar 1993).Moreover, it presents a conspicuous, sclerotized epipharynx that is used to scrape on the bottom of the streams where it lives.
Notes on habitats.The width of the sampled rivers varied from 8-10 m, the stream bed was composed of sand, small rocks and boulders.Rio Hermes water temperature was 27.5 °C, pH 7.9 and conductivity 173.2 µScm -1 , while and Rio Sambito water temperature was 26.5 °C, pH 7.3 and conductivity 100.7 µScm -1 .Specimens were collected in the shallowest portions of the rivers (5 -30 cm).
Larvae and pupae were found in deciduous leaves accumulated on the rocks located on the margins of the Rio Hermes; larvae occupied the submerged side of the leaves and pupae the upper side above the water, very exposed to the sunlight.At Rio Sambito larvae were collected from submerged rocks and pupae above the water, on rocks exposed to strong sunlight (Fig. 43).
Pupae resist the high temperatures of the exposed rocks, and retain the larval exuviae with their terminal processes (Hamada, pers. com.).They adhere to the rocks by the claws of the larval exuviae, keeping a vertical position.
catalogued 100 species for the Neotropics, and eight more were subsequently described for the Region.Of this number, the subgenus A. (Lophomyidium Cordero) includes only the following eight species: A. archboldi Wirth, A. delpontei Cavalieri and Chiossone, A. fusculus (Coquillett), A. ocumare (Ortiz), A. setosilateralis Borkent and Picado, A. taeniatus Macfie, A. tapantiensis Borkent and Picado, and A. uruguayensis Cordero.Larval and pupal stages are only known for A. fusculus, briefly described by