Cryptochironomus reshchikovi, Silva, Fabio Laurindo Da, Strixino, Susana Trivinho & Oliveira, Heliana Rosely Neves, 2010

Silva, Fabio Laurindo Da, Strixino, Susana Trivinho & Oliveira, Heliana Rosely Neves, 2010, New species of Cryptochironomus Kieffer, 1918 (Diptera: Chironomidae: Chironominae) from Brazil, Zootaxa 2614, pp. 18-32 : 27-30

Cryptochironomus reshchikovi sp. n.

(Figs. 25–36)

Type material. Holotype male with larval and pupal exuviae, BRAZIL: São Paulo State, São Carlos, Monjolinho stream, iv/2008, H. R. N. Oliveira & W. Chiba. Paratypes: 1 pharate male with larval exuviae, as holotype except for 29/vii/2009, F. L. Silva & S. Trivinho-Strixino; 2 pupae, BRAZIL: Mato Grosso do Sul, Três Lagoas, Jupiá reservoir, 9/xii/2000, F. O. Roque; 1 female with larval and pupal exuviae, BRAZIL: São Paulo State, São Carlos, Monjolinho stream, 29/vii/2009, F. L. Silva & S. Trivinho-Strixino; 1 female with larval and pupal exuviae, BRAZIL: São Paulo State, São Carlos, Mayaca pond, 9/xii/2000, S. Trivinho- Strixino.

Etymology. Named in honour of Dr. Alexey Reshchikov of St. Petersburg, in recognition for his friendship, kindness and continuous support.

Diagnostic characters. Cryptochironomus reshchikovi differs from other Cryptochironomus species by combination of the following characters. Adult male: hypopygium with superior volsella pad-like, with 1 long setae apically; inferior volsella elongate, completely covered by superior volsella with 1 long seta; gonostylus inflated. Pupa: S I with anterolateral and anteromedian shagreen patches; anal lobe with 70–80 taeniae. Larva: antenna with 6 segments.

Description. Male (n = 1)

Dimensions. Total length 3.8 mm. Wing length 1.57 mm. Total length/wing length 2.43. Wing length/ length of profemur 1.95.

Coloration. Head yellowish brown, flagellum and maxillary palp brown. Thorax yellowish brown with brown mesonotal stripes and posteromedian region darkened. Scutellum pale brown. Wing membrane transparent, veins pale brown, without spots. All leg segments and abdomen including hypopygium brown.

Head. Eyes ratio 2.69. Flagellum 1.16 μm long; AR 2.31. Palpomere 1–5 lengths (in μm): 26; 37; 133; palpomere 4–5 missing. Frontal tubercles 17 μm long, 6 μm wide. Temporal setae irregularly biserial. Clypeus with 16 setae.

Thorax. Antepronotum with 5 setae. Acrostichals biserial, beginning near antepronotum; dorsocentrals 6, uniserial; prealars 4; supraalar 4. Scutal tubercle present.

Wing 0.20 mm wide. Membrane without setae. Brachiolum with 2 setae; R with 20 setae; R1 with 18 setae; R4+5 with 17 setae. Squama fringed. R2+3 ending close to, but distinctly separate from R1. VR = 1.36.

Legs. Mid and hind leg with two pseudospurs on Ta1–4. Tarsal claws on all legs slender and hook-like, pulvilli well developed. Lengths and proportions of legs as in Table 4.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV p1 804 588 1020 490 392 314 176 1.73 1.76 1.37 p2 706 686 392 196 137 98 78 0.57 3.50 3.55 p3 804 843 588 294 255 157 98 0.70 2.78 2.80 Hypopygium ( Figs. 31–32 ). Tergite IX with 12 strong setae. Anal point slender, tapering towards broader apex. Superior volsella pad-like, with 1 long setae apically. Inferior volsella elongate, completely covered by superior volsella with 1 long seta ( Fig. 32 ). Gonostylus inflated about 2.42 times as long as wide. HR 1.24.

FIGURES 25–30. Cryptochironomus reshchikovi sp. n., pupa. 25. Cephalic tubercles. 26. Thorax. 27. Basal ring. 28. Abdomen. 29. Sternite I. 30. Armature and reticulation on abdominal segments: a. hook on 2nd segment, b. spines on 4th segment, c. spines on 7th segment, d. spines on 8th segment, e. reticulation on 4th segment.

Pupa (n = 4 unless otherwise stated)

Dimension. Abdomen [3.2] 3.1–3.6, 3.3 mm long.

Coloration. Exuviae pale brown.

Cephalothorax (Figs. 25–27). Cephalic tubercles [67] 59–90, 75 μm long, conical, apically pointed; frontal setae [45] 29–45, 37 μm long, placed subapically (Fig. 25). Wing sheath [1.01] 0.90–1.10, 0.98 mm long. Thorax extensively granulose; scutal tubercle present; prealar tubercle absent; antepronotals 2, precorneals 2, dorsocentrals 4 (Fig. 26). Basal ring rounded (Fig. 27).

Abdomen (Figs. 28–30). Shagreenation on T I–VI covering most of tergite and with distinctly reticulation; T VII–VIII fine reticulate and with small spines (Fig 30e); anal lobe with small spines. Posterior row of recurved hooks, interrupted medially, extending nearly on 1/3 the width of T II (Figs. 28, 30a); spines on 4th, 7th and 8th segments as in figures 30b, 30c and 30d, respectively. T II–VIII and S I–III with posterior row of spines; S IV–SV with few and small spines; S VII–SVIII spines absent or reduced (Fig 28). S I with anterolateral and anteromedian shagreen patches (Fig. 29). Pedes spurii B present on segment II. Pedes spurii A present in segment IV. Abdominal chaetotaxy as in Table II. Anal lobe with complete fringe of about [70] 70–80 taeniae.

4th instar larva (n = 4 unless otherwise stated)

Coloration. Body reddish; head yellowish, postmentum and frontoclypeus without dark areas. Procercus and anal setae pale brown. Posterior parapod claws all pale yellowish.

Head [359] 273–359, 329 μm long, [312] 265–336, 303 μm wide.

Antenna ( Fig. 33 ) [122] 122–159, 137 μm long with 6 segments; basal antennal segment [67] 63–78, 69 μm long, with ring organ [39] 39–41, 40 μm from base. AR [1.21] 0.92–1.21, 1.01. Antennal blade [39] 39–41 (2), arising in distal 1/3 of segment 3, reaching almost antennal apex. Style present on segment 3.

Maxilla. Basal palp segment [49] 39–49, 44 μm long, [20] 12–20, 16 μm wide, with ring organ [16] 8–16, 10 μm from base.

Labrum ( Fig. 34 ). SI short, blade-like on small plate; SII longer, more robust blade-like, [55] 52–55 μm long; SIII very short, seta-like; SIVa elongated, 3 segmented; SIVb short, arising behind first segment of SIVa. Pecten epipharyngis divided in 3 lobes. Premandible with 4 teeth, progressively decreasing in size towards base; brush present.

Mandible ( Fig. 35 ) [108] 100–141 μm long with apical tooth and 2 inner triangular teeth dark brown. Seta subdentalis slender, base wider than apex.

Mentum ( Fig. 36 ). With a large middle white tooth and 5 dark lateral teeth; outermost notched. Ventromental plate about [1.04] 1.03–1.07, 1.05 times as long as width of mentum, course striated.

Abdomen. Procercus [0.79] 0.93–0.87 (3) times as long as wide, with 7 anal setae. Posterior parapod with simple claws.

Remarks. The male of C. reshchikovi is similar to C. imitans Saether , but can be distinguishable by the AR and wing length, lower in C. reshchikovi . The pupae of C. reshchikovi are separable from other Neotropical know species by the higher cephalic tubercle and number of taeniae on the anal lobe. The larvae of C. reshchikovi seem to be closely related to C. imitans Saether and C. sorex Townes , however the three species can be separated based on number of antennal segments. C. reshchikovi has six, while the other species have five antennal segments. The larvae of C. reshchikovi were collected on sandy bottom of streams and ponds.

Figures

FIGURES 31 – 36. Cryptochironomus reshchikovi sp. n., male (31 – 32) and larva (33 – 36). 31. Hypopygium. 32. Superior and inferior volsellae. 33. Antenna. 34. Labrum, epipharynx and premandible. 35. Mandible. 36. Mentum.