Paratanytarsus corbii, Trivinho-Strixino, Susana, 2010

Trivinho-Strixino, Susana, 2010, Two new species of Paratanytarsus (Diptera: Chironomidae) from southeast of Brazil, Zootaxa 2726, pp. 59-67 : 60-65

Paratanytarsus corbii sp. n.

( Figs. 1–17 )

Material examined. Holotype: adult male with pupal and larval exuviae (in Euparal), Brazil, São Paulo, Américo Brasiliense, Anhumas Reservoir (21° 42’ S, 48° 00’ W), leg. S. T. Strixino, 24/x/2000. Paratypes (mostly in Euparal): 1 male with pupal exuviae same data as holotype except for 20/x/2000; 1 male as previous; 1 male and 1 female with pupal and larval exuviae in the same slide, same data as holotype; 1 pupa with pharate male same data as holotype except for 19/x/2000; 1 pupal exuviae same data as holotype except for 20/x/2000; 5 larvae same data as holotype except for 25/x 2000, leg. J. J. Corbi.

Etymology. Named in honour to Dr. Juliano José Corbi who first collected the larvae of this species in the Anhumas Reservoir.

Diagnosis. Adult male: wing membrane transparent, covered with setae; AR 0.75–0.89; LR 1.66–2.00; hypopygium with anal tergite bands separated; anal point long, without anal crests; superior volsella somewhat quadrangular, digitus well developed; median volsella with several spatulate and setiform lamellae distally. Adult female: wing membrane as in male; fore tibia with 1 short spur, middle and hind tibia with combs bearing 1 spur; genitalia with GpVIII divided into 2 lobes; floor under vagina of moderate size; notum 1.5 times as long as seminal capsules; GcIX without seta. Pupa: frontal apotome and cephalic tubercles granulose; thoracic horn elongate, with distal fringe of setae; thorax with strong granulation; scutal tubercle present; tergite III–V with longitudinal lateral paired patches of spines; IV and V with 2 circular field of short spines anteriorly in addition with 3 long spines; pedes spurii B absent. Larva: clypeal seta S3 simple; pecten epipharyngis with three indented scales; antenna 5– segmented, 1.5 times shorter than head length; Lauterborn organs large on pedicels longer than antennal segments 3–5.

Description. Male (n = 4 unless otherwise stated)

Dimensions. Small, length c. 2.0 mm. Wing length 1050 µm [1050 –1250].

Coloration. Head pale, yellowish green, flagellum and maxillary palp yellowish. Thorax green yellowish, postnotum slightly brownish, scutellum greenish. Wing membrane transparent, veins yellowish. Abdomen yellowish green. Legs yellowish.

Head. Eyes ratio 1.09 [1.00–1.10]. Antenna with 13 flagellomeres; antennal flagellum 756 µm long [756– 850]; AR = 0.75 [0.75–0.89]. Palpomeres 1–5 length (3): 21, 25 [25–31], 69 [56–69], 75 [75–88], 137 [137–156] µm. Frontal tubercles 24 [20–27] µm long (3) ( Fig. 1 ). Temporal setae 8–9, uniserial. Clypeus 52 [43–60] µm long with 18 [13–18], (3) setae.

Thorax. Acrostichals 12–14 (3) biserial, beginning near antepronotum; dorsocentrals 7, uniserial; prealar 1, scutellars 4. Each haltere with 4 setae (1). Scutal tubercle absent.

Wing 300 [282–337] (3) µm wide. C ending close to R4+5, before wing apex; R4+5 ending slightly distally to apex of M3+4; R2+3 indistinct. Membrane covered with setae, becoming dense in distal ½. Setae present on all veins except M and basal third of M1+2; brachiolum with 1 (3) seta; squama bare. RM proximal to FCu, VR= 1.37 [1.34–1.35] (3).

Legs. Fore tibia with short slender white spur 8 [8–14] µm long. Mid and hind tibiae with black combs, each tibia with only one spur. Lengths and proportions as Table 1.

fe ti ta1 ta2 ta3 ta4 ta5 LR

p1 463–519 275–312 550–519 281–331 212–250 156–194 75 1.66–2.00 p2 487–562 400–425 219–231 110–125 80–106 50–69 44 0.54– 0.55 p3 531–619 481–544 300–350 181–206 150–194 94 50–56 0.62– 0.64 Hypopygium ( Figs. 2, 3 ). Anal tergite bands separated; median setae absent. Anal point long and slender 22 [22–30] µm long (3); anal crests absent. Superior volsella ( Fig 4 ) somewhat quadrangular, with five lateral robust setae; digitus well developed, extending well beyond posteromedian corner of superior volsella. Inferior volsella bent in median part, extending beyond base of gonostylus; tip slightly folded. Median volsella short 21 [15–21] µm long (3), with several spatulate and setiform lamellae distally ( Fig 5 ).

Female (n = 1). Dimension and coloration. Length near 1.7 mm. Wing length 1019 Μm. Coloration as in male. Head. Eyes bare, with little dorsomedian extension. Eyes ratio 1.50. Antennal flagellum slightly shorter than palp; Fm 2–5 length: 42, 38, 38, 46 µm. Palpomeres 1–5 length: 14, 15, 42, 51, 115 µm. Frontal tubercles not discernible in slide preparation. Temporal setae 7. Clypeus 50 µm long, with 16 setae.

Thorax. Acrostichals 13, biserial, beginning near antepronotum; dorsocentrals 6; prealar 1; scutellars 4. Scutal tubercle absent.

Wing. 312 Μm wide. VR = 1.43. Macrotrichia covering all cells and veins except M and basal third of M1+2. R 2+3 not distinct; R4+5 ends proximal of M3+4.

Legs. Fore tibia with one short spur, 12 µm long; mid and hind tibiae with combs, each one bearing one black spur. Lengths and proportions as in Table 2.

fe ti ta1 ta2 ta3 ta4 ta5 LR p1 375 244 – – – – – – p2 406 306 175 94 68 50 44 0.57 p3 431 406 237 144 119 62 50 0.58

Genitalia ( Fig. 6 ). Sternite VIII bearing 12 setae distributed regularly; SVIII form a short size floor under anterior part of vagina; posteromedian contour of SVIII rounded. GpVIII divided, and covered with short caudolateral microtrichia. Notum as long as free rami. Notum 1.5 as long as seminal vesicles. Seminal vesicles ovoid, near 40 Μm long, without neck. Spermathecal duct nearly straight. GcaVIII straight, running diagonally to posterior corner of SVIII. GcIX without setae.

Pupa (n = 4). Dimension. Length of abdomen: male 1.98 (2) mm; female 1.88 (2) mm.

Cephalothorax. Frontal setae elongate, slender, 57 µm long arising apically from prominent cephalic tubercles. Frontal apotome, including cephalic tubercles granulose ( Fig. 8 ). Thoracic horn elongate, c. 328 µm long, with fringe of setae on distal ½ ( Fig. 9 ). Thorax with strong granulation close to anterior median suture; scutal tubercle short ( Fig. 7 ). Wing sheath with prominent nose; pearl row absent. Chaetotaxy of thorax: 3 precorneals (Pc1-3) and 2 lateral antepronotals (LAps1,3) present on each side. Pc1 situated in front and ventral of the basal ring of thoracic horn. LAps1 situated in front and at the same level as Pc1; LAps3 situated more ventrally than Pc2-3. Dc 1-4 situated in two groups, widely separated.

Abdomen. Tergite I without shagreen; II with central transverse field of fine shagreen; III with posterior pair of patches of long spines bands; bands strongly curved and divergent posteriorly; IV and V with lateral paired patches of spines ( Fig. 10 ), and 2 circular field of short spines anteriorly in addition with 3 long spines ( Fig.11 ); VI to VIII without shagreen. Hook row continuous, occupying ½ width of segment II. Pedes spurii B absent. Segment VIII with posterolateral combs consisting of 4–5 marginal and 5–6 overlapping ventral teeth ( Fig. 12 ). Anal lobe with 23–24 taeniae and 1 large dorsal taenia on each side. Abdominal setation as in Table 3.

segment O Te S L I 0 2 0 0 II 0 2 2 3 III 0 4 2 3 IV 0 4 4 3 ST V 0 4 4 3 ST VI 0 4 4 4 T VII 0 4 2 4 T VIII 0 1 1 5 T

4th instar larva (n =5). Dimension. Small, total length 3.20 mm [2.89–3.58].

Head. Length 312 µm [294–325], width 225 µm [212–237]. Clypeal seta (S3) simple ( Fig. 13 ). Antenna ( Fig. 14 ). With 5 segments placed on prominent pedestal, 61 µm long [58–65]; basal segment 123 µm, longer than flagellum and slightly bent outside; basal ring organ and small seta in proximal ½ part; segment 2 (31 µm) slightly longer than segments 3–5 (14, 6, 5 µm); Lauterborn organs large, pedicels near 31 Μm long, longer than segments 3–5.

Labrum. Labral seta SI pectinate, bases fused; SII distally plumose, situated on short pedestal; SIII simple, seta-like; SIV not discernible. Labral lamella well developed. Pecten epipharyngis consisting of 3 distally serrated scales ( Fig. 15 ). Premandible with 2 teeth ( Fig. 16 ); brush well developed.

Mandible ( Fig 17 ). 100µm long [92–108] with dorsal, apical and two inner teeth brown.

Mentum ( Fig. 18 ). 68 µm long [61–72] with median tooth slightly notched laterally and 5 pairs of lateral teeth all brownish. Ventromental plates longer than mentum (81 µm) close together medially.

Abdomen with anal tubules shorter than parapods. Claws of posterior parapods simple.

Remarks. The long and slender anal point and the absence of anal crests are the main characteristics that differentiate Paratanytarsus corbii sp. n. male, from other species of the genus, except P. silentii sp. n. and an undescribed species ( Bolton et al. 2010, in press); the length of the anal point and the shape of median volsella separate P. c o r b i i from the latter. The arrangement of spines on tergites III–V and the absence of pearl row distinguish the pupa of P. co r b ii from other species. The length of pedicels and the pecten epipharyngis design differentiate the larvae of P. c o r b i i from other Paratanytarsus .

Figures

FIGURES 1 – 6. Paratanytarsus corbii sp. n., male (1 – 5) and female (6). 1. Frontal tubercle. 2. Hypopygium, dorsal view left, ventral view right. 3. Hypopygium lateral view. 4. Superior volsella. 5. Median volsella. 6. Genitalia. Scales: Fig 1 = 25 µm; Figs. 2, 3, 6 = 100 µm; Figs. 4, 5 = 50 µm.

FIGURES 7 – 12. Paratanytarsus corbii sp. n., pupa. 7. Thorax, lateral view. 8. Cephalic tubercles. 9. Thoracic horn. 10. Abdomen tergites. 11. Ornamentation of tergites III – V. 12. Comb. Scales: Figs. 7, 10 = 500 µm; Figs. 8, 9 = 100 µm; Fig. 12 = 50 µm.

FIGURES 13 – 18. Paratanytarsus corbii sp. n., larva. 13. Clypeal seta S 3 and antennal tubercles. 14. Antenna. 15. Pecten epipharyngis. 16. Premandible. 17. Mandible. 18. Mentum and ventromental plates. Scale: Fig. 15 = 50 µm; Figs. 14, 16, 17, 18 = 100 µm.