Cryptochironomus brasiliensis, 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 : 19-23

Cryptochironomus brasiliensis sp. n.

(Figs. 1–12)

Type material. Holotype male with larval and pupal exuviae, BRAZIL: São Paulo State, São Carlos, Monjolinho stream, 29/vii/2009, F. L. Silva & S. Trivinho-Strixino. Paratypes: 1 female with pupal and larval exuviae, as holotype. 2 males with pupal exuviae, as holotype except for Mayaca pond, 2/xii/2000, S. Trivinho-Strixino. 1 male with pupal exuviae, as previous except for 9/xii/2000.

Etymology. This species is named after the country from which it was collected using the Latin spelling of Brazil.

Diagnostic characters. Cryptochironomus brasiliensis differs from other Cryptochironomus species by combination of the following characters. Adult male: hypopygium with broader superior volsella, with 3 long setae apically; inferior volsella stout, completely covered by superior volsella, with 3 long setae. Pupa: abdomen distinctly reticulate on T I–VI; faint reticulation on T VII–VIII; anal lobe with 117–146 filaments. Larva: head capsule length of about 492–531 μm, AR 0.80–1.05.

Description. Male (n = 4 unless otherwise stated)

Dimensions. Total length [6.3] 4.61–6.29, 5.25 mm (3). Wing length [2.45] 2.27–2.45, 2.36 mm. Total length/wing length [2.57] 1.96–2.57, 2.22 (3). Wing length/length of profemur [2.50] 2.07–2.50, 2.23.

Coloration. Head yellowish brown, flagellum and maxillary palp pale brown. Thorax yellowish brown with brown mesonotal stripes and posteromedian region darkened. Scutellum pale brown. Wing membrane transparent and veins pale brown, without spots. Legs dark brown with medium third of femur, tibia and half proximal of Ta1 pale brown. Abdomen including hypopygium brown.

Head. Eyes ratio [0.82] 0.77–1.06, 0.88 (3). Flagellum [1172] 1172–1328, 1287 μm long; AR [2.06] 2.06– 2.78, 2.50. Palpomeres 1–5 lengths (in μm): [49] 49–51 (2); [84] 75–84 (2); [253] 231–253 (2); [190] 153– 190 (2); [271] 202–271 (2). Frontal tubercles [31] 20–31, 27 (3) μm long, [16] 8–16, 12 (3) μm wide. Temporal setae 27–30 (2), irregularly biserial. Clypeus with [21] 18–21, (3) setae.

Thorax. Antepronotum with [14] 14 (1) setae. Acrostichals [22] 22 (1), biserial, beginning near antepronotum; dorsocentrals [14] 14 (1), partly biserial; prealars [5] 5 (1); supraalar [1] 1 (1). Scutellum with [21] 21 (1) biserial setae. Scutal tubercle present.

Wing [0.71] 0.65–0.71, 0.68 mm wide. Membrane without setae. Brachiolum with [2] 2 setae; R with [23] 22–24 setae; R1 with [18] 18–22 setae; R4+5 with [25] 25–33 setae. Squama fringed. R2+3 ending close to, but distinctly separate from R1. VR = [1.09] 1.02–1.10, 1.08.

Legs. Mid 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 1 .

Hypopygium ( Figs. 7–8 ). Tergite IX with [13] 13–16 (2) strong setae. Anal point slender, apex wider than base, [108] 108–137, 118 μm long. Superior volsella broad, with [3] 3 (1) long setae apically. Inferior volsella stout, completely covered by superior volsella, with [3] 3 (1) long setae ( Fig. 8 ). Gonostylus short about [2.17] 1.87–2.90, 2.40 times as long as wide. HR [0.78] 0.75–1.03, 0.88.

Pupa (n = 4 unless otherwise stated)

Dimension. Abdomen [5.6] 4.5–5.6, 4.9 mm long.

Coloration. Exuviae pale brown.

Cephalothorax (Figs. 1–3). Cephalic tubercles [114] 86–134, 106 μm long, conical, apically pointed; frontal setae [45] 24–45, 36 μm long, placed subapically (Fig. 1). Wing sheath [1.41] 1.37–1.41, 1.38 mm long. Thorax extensively granulose (Fig. 2); scutal tubercle present; prealar tubercle absent; antepronotals 2 (3), precorneals 2, dorsocentrals 4. Basal ring constricted medially (Fig. 3).

Abdomen (Figs. 4–6). Shagreenation on T I–VI covering most of tergite, with fine reticulations; T VII and anal lobe finely reticulate (Fig. 6d) and with small spines; T VIII with small spines. Posterior row of recurved hooks, interrupted medially, extending nearly on 1/3 the width of tergite II (Figs. 4, 6a); spines on 4th and 8th segments as figures 6b and 6c, respectively. T II–VIII and S I–V with posterior row of spines; S VI–VIII with few spines (Fig. 4). S I with anterolateral shagreen patches (Fig. 5). Pedes spurii B present on segment II. Pedes spurii A present in segment IV, reduced to few spinules. Abdominal chaetotaxy as in Table 2 . Anal lobe with complete fringe of about [134] 117–146 taeniae.

4th instar larva (n = 2 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 [531] 492–531 μm long, [453] 422–453 μm wide.

Antenna ( Fig. 9 ) [145] 145–176 μm long, with 5 segments, basal antennal segment [65] 65–80 μm long, with ring organ [41] 41–50 μm from base. AR [0.80] 0.80–1.05. Antennal blade [39] 39–45, arising in distal 1/3 of segment 2, reaching almost antennal apex. Style present on segment 2.

Maxilla. Basal palp segment [47] 47–59 μm long, [14] 14–18 μm wide, with ring organ [6] 6– 12 μm from base.

Labrum ( Fig. 10 ). SI short, blade-like; SII longer, more robust blade-like, [57] 51–57 μm long; SIII very short, seta-like; SIVa elongated, 3 segmented. Pecten epipharyngis divided in 3 lobes. Premandible with 4 teeth, progressively decreasing in size towards base; brush present.

Mandible ( Fig 11 ) [110] 108–110 μm long with apical tooth and 2 inner triangular teeth dark brown. Seta subdentalis slender, base wider than apex.

Mentum ( Fig 12 ). With a large middle white tooth and 5 dark lateral teeth; outermost notched. Ventromental plate about [1.25] 1.23–1.25 times as wide as width mentum, course striated.

Abdomen. Procercus [0.84] 0.74–0.84 times as long as width, with 7 anal setae. Posterior parapod with simple claws.

FIGURES 1–6. Cryptochironomus brasiliensis sp. n., pupa. 1. Cephalic tubercles. 2. Thorax. 3. Basal ring. 4. Abdomen. 5. Sternite I. 6. Armature and reticulation on abdominal segments: a. hook on 2nd segment, b. spines on 4th segment, c. spines on 8th segment, d. reticulation on 4th segment.

Remarks. The male of C. brasiliensis can separated from C. imitans Saether based on shape of inferior volsella, broader with 3 setae in C. brasiliensis , instead of 1–2 setae as in C. imitans . The pupae of C. digitatus Malloch , C. sorex Townes and C. imitans Saether are the most similar to pupa of C. brasiliensis apart from abdomen and cephalic tubercle lengths and the number of anal lobe filaments. The larvae of C. brasiliensis seem to be closely related to C. conus Mason and C. imitans Saether except for the length of the second antennal segment. The larvae of C. brasiliensis are relatively common on aquatic system from southeast Brazil and were collected on sandy in bottom of streams and ponds.

Figures

FIGURES 7 – 12. Cryptochironomus brasiliensis sp. n., male (7 – 8) and larva (9 – 12). 7. Hypopygium. 8. Superior and inferior volsellae. 9. Antenna. 10. Labrum, epipharynx and premandible. 11. Mandible. 12. Mentum.

Tables

TABLE 1. Lengths (in μm) and proportions of legs of Cryptochironomus brasiliensis sp. n., male (n = 4).

fe	ti	ta1	ta2	ta3
p1 [980] 980–1137, 1064	[1235] 784–1235, 951	[1667] 1176–1667, 1436	[863] 647–863, 760	[667] 510–667, 598
p2 [1098] 941–1098, 990	[1039] 882–1039, 961	[922] 549–922, 667	[392] 294–392, 338	[275] 196–275, 245
p3 [1078] 1020–1078, 1049	[1020] 941–1078, 1054	[686] 608–882, 740	[353] 314–451, 377	[275] 235–314, 294
continued.
ta4	ta5	LR	BV	SV
p1 [588] 471–588, 525	[275] 196–275, 225	[1.35] 1.35–1.60, 1.53	[1.62] 1.62–1.66, 1.64	[1.33] 1.33–1.52, 1,41
p2 [176] 157–176, 167	[118] 98–137,118	[0.89] 0.61–0.89, 0.69	[3.18] 2.86–3.18, 3.01	[2.32] 2.32–3.39, 3.02
p3 [196] 157–196, 186	[98] 98–137, 113	[0.67] 0.65–0.75, 0.70	[3.02] 2.74–3.20, 2.95	[3.06] 2.53–3.06, 2.88

TABLE 2. Pupal abdominal chaetotaxy of C. brasiliensis sp. n., C. mantiqueira sp. n. and C. reshchikovi sp. n. Abbreviations: O = O – setae, T = Tergite, S = Sternite, L = Lateral, Ta = Taenia.

Segment	C. brasiliensis sp. n. O T S L	C. mantiqueira sp. n. O T S L	C. reshchikovi sp. n. O T S L
I II	1 1 1 5 2 2	1 1 1 5 2 2	1 1 1 5 2 2
III	1 5 2 2	1 5 3 2	1 5 3 2
IV V	1 5 2 2 1 5 2 2	1 5 3 2 1 5 2 2	1 5 3 3 1 5 3 2
VI	1 5 2 4Ta	1 5 3 4Ta	1 5 3 4Ta
VII VIII	1 5 3 4Ta 1 1 1 5Ta	1 5 3 4Ta 1 1 1 5Ta	1 4 3 4Ta 1 1 1 5Ta