Kribiodorum amazonicum, Dantas & Hamada, 2021
Dantas, Galileu P. S. & Hamada, Neusa, 2021, Discovery of Kribiodorum Kieffer (Diptera: Chironomidae) in the Neotropical region: a new species from Brazilian Amazon rainforest, Zootaxa 5052 (1), pp. 128-136: 129-134
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Kribiodorum amazonicum sp. n.
Type material: Holotype, adult male: BRAZIL, Amazonas, Humaitá municipality, first-order tributary of Beem stream, 07°33’13” S, 63°00’59” W, 17.viii.2009, leg. G.P.S. Dantas ( INPA) GoogleMaps . Paratypes: 2 males and 1 female, as holotype ( INPA) .
Etymology. The specific epithet refers to the Amazonian rainforest, the biome in which this new species was collected.
Diagnosis. Wing base pale; costal cell mostly pale; cell m 1+2 with four pale areas; fore femur strongly expanded at subapex, dark, with a median small pale band; mid femur almost completely dark, except for a small, pale basal band. Digitus robust, broad, and somewhat paddle shaped.
Description. Adult male (n= 3).
Body size and proportions. Total length 3.50–3.80 mm. Wing length 1.78–2.13 mm. Total length/wing length 1.97. Wing length/length of profemur 1.77–1.88.
Coloration. Eyes black. Head capsule and pedicel dark brown; antennal flagellum and palp brown. Thorax dark brown. Wing: brown veins, membrane with light brown undertone, with pattern of dark spots ( Fig. 2B View FIGURE 2 ). Front leg: femur brown, with a median pale brown band; tibia with basal 2/3 pale, 1/3 apical dark brown; ta 1–2 pale brown, darker at base and apex; ta 3–5 brown ( Figs. 2A and 2C View FIGURE 2 ). Mid leg: femur dark brown, with pale basal and apical ends; tibia completely dark brown; ta1 dark brown, with median pale band; ta 2–3 pale, with brown apex; ta 4–5 brown ( Fig. 2D View FIGURE 2 ). Hind leg: femur dark brown, with light brown base and apex; tibia dark brown, with basal light band; ta 1 with base and apex dark brown, median region pale; ta 2–3 pale, with brown apex; ta 4–5 brown ( Fig. 2E View FIGURE 2 ). Abdomen dark brown, hypopygium pale ( Fig 2A View FIGURE 2 ).
Head. Eyes bare, with well-developed dorsomedian extensions. Antenna with 13 flagellomeres; apical flagellomere 698–730 μm long; AR 1.45–1.49. Frontal tubercles absent or in shape of minute swellings. Tentorium 133–142 μm long, heavily sclerotized. Temporal setae 6–9 on each side. Clypeus with 22–30 setae. Lengths of palpomeres 1–5 (in μm): 33–34, 40–42, 96–99, 160–162, 186–195; third palpomere with 4 sensilla clavata subapically, 18–19 μm long. Fifth palpomere / third palpomere ratio 1.94–1.97.
Thorax. Ac 14, restricted to anterior region of scutum; Dc 11–13 on each side, uniserial; Pa 4–5; Scts 5. Scutum slightly projected anteriorly, overreaching antepronotum.
Wing ( Fig. 2B View FIGURE 2 ). VRCu 1.18–1.23. Membrane finely punctate, without macrosetae. Brachiolum with 2 setae, R with 11–17, R 1 with 8–11, R 4+5 with 4–9. Anal lobe reduced.
Legs ( Figs. 2C–E View FIGURE 2 ). Foreleg femur markedly expanded at subapex, tibia with a curved spine, about 35 μm long. Tibial combs of mid and hind legs narrowly separated; shorter, higher comb with distinct spur (22–30 μm long), broader shallower comb without spur. Lengths and proportions of legs as in Table 1 View TABLE 1 .
Hypopygium ( Fig. 3A–C View FIGURE 3 ). Anal tergite with open V-shaped bands ( Fig. 3A View FIGURE 3 ), flanking 10–16 dorsal setae; about 11–14 smaller lateral setae on each side. Posterior margin of tergite IX somewhat wedge-shaped. Anal point spatulate, 56–73 μm long, 12–13 μm wide, protruding from anal tergite by 30–35; dorsal crest well developed ( Fig. 3A View FIGURE 3 ). Superior volsella microtrichiose, base elevated bearing 6 setae, basal limit difficult to discern, apically tapered ( Fig. 3C View FIGURE 3 ); digitus 55–57 μm long, bare, robust, curved, somewhat paddle-shaped, base covered by superior volsella. Median volsella pad-shaped, bearing 6 medially directed setae ( Fig. 3C View FIGURE 3 ). Inferior volsella 114–120 μm long, microtrichiose, bearing about 22 apical/subapical bristles, some with forked apex ( Fig. 3A View FIGURE 3 ). Phallapodeme 67–72 μm long; transverse sternapodeme 36–42 μm long, with distinct oral projections ( Fig. 3B View FIGURE 3 ). Gonocoxite 125– 138 μm long. Gonostylus 149–158 μm long, broadest subasally, narrowing abruptly at the apex, forming a lobe. HR 0.84–0.87; HV 2.20–2.40.
Adult female (n= 1).
Body size and proportions. Total length 3.60 mm. Wing length 2.14 mm. Total length/wing length 1.68. Wing length/length of profemur 1.97.
Coloration. Eyes black. Head capsule and pedicel dark brown; antennal flagellum and palp brown. Thorax dark brown ( Fig. 4B View FIGURE 4 ). Wing: brown veins, membrane with pale brownish undertone, with pattern of dark spots ( Fig. 4C View FIGURE 4 ). Front leg: femur brown, with a median light-brown band; tibia with basal 2/3 light-brown, 1/3 apical dark brown. Mid leg: femur dark brown, with slightly lighter basal and apical ends; tibia completely dark brown; ta1 dark brown, with median light-brown band; ta 2–3 light brown, with dark brown apex; ta 4–5 brown. Hind leg: femur dark brown, with light brown base and apex; tibia dark brown, with basal light band; ta1 with base and apex dark brown, median region light brown; ta 2–3 light brown, with dark apex; ta 4–5 dark brown. Abdomen dark brown.
Head ( Fig. 4A View FIGURE 4 ). Eyes bare, with well-developed dorsomedian extensions. Antenna with 6 flagellomeres; apical flagellomere 100 μm long; AR 0.28. Frontal tubercles absent or in shape of minute swellings. Tentorium 113 μm long, heavily sclerotized. Temporal setae 8 on each side. Clypeus with 47 setae. Lengths of palpomeres 1–5 (in μm): 43, 47, 130, 207, 240; third palpomere with 3 sensilla clavata subapically, 20 μm long. Fifth palpomere / third palpomere ratio 1.85.
Thorax ( Fig. 4B View FIGURE 4 ). Ac 16, restricted to anterior region of scutum; Dc 7–9 on each side, uniserial; Pa 4–5; Scts 6. Scutum projected anteriorly, slightly overreaching antepronotum.
Wing ( Fig. 4C View FIGURE 4 ). VRCu 1.24. Membrane finely punctate, without macrosetae. Brachiolum with 3 setae, R with about 21, R 1 with about 17, R 4+5 with about 22. Anal lobe reduced.
Legs. Foreleg femur markedly expanded, tibia with a curved spine, 40 μm long. Tibial combs of mid and hind legs narrowly separated; shorter, higher comb with distinct spur (about 30 μm long), broader shallower comb without spur. Lengths and proportions of legs as in Table 2 View TABLE 2 .
Genitalia ( Fig. 4D–E View FIGURE 4 ). Notum 187 μm long, thin, with short rami. Gonocoxapodemes strongly sclerotized, basally curved, and medially projected. Coxosternapodeme heavily sclerotized, arched, sinuous at the medial end. Gonapophysis VIII ( Fig. 2C View FIGURE 2 ) comprising an elongate medialmost lobe, essentially continuous with inner contour of vagina, microtrichiose apico-medially, and a distinct posterolateral lobe of similar size to medial lobe, lying posterior to, and separate from medial lobe, microtrichiose with many strong, hyaline, medio-apically directed spines, posterobasal margin setose. Labia well developed, hyaline, without microtrichia. Gonocoxite IX small, not exteded laterally. Tergite IX broad, densely setose, undivided. Postgenital plate well-developed, triangular, blunt apically, covered with macrotrichia. Seminal capsule oval, 62 um long, 52 μm wide, with well-developed neck; spermathecal duct sinuous. Cerci large, somewhat quadrate, 125 μm long.
Distribution and ecological notes. The new species is known only from the type locality in northern Brazil ( Fig. 5 View FIGURE 5 ). The adults were obtained from submerged wood, with bark and in an intermediate stage of decomposition (firm but not hard) and maintained under laboratory conditions ( Fig. 1 View FIGURE 1 ). The wood pieces were collected in a stream about 3 meters wide, located in a well-preserved area, surrounded by dense forest with closed canopy.
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