Pseudochironomus ruah, Trivinho-Strixino, 2017

Trivinho-Strixino, Susana, 2017, Brazilian Pseudochironomini (Diptera: Chironomidae) Part 1. New Pseudochironomus Malloch from highlands, Zootaxa 4317 (1), pp. 134-154 : 136-143

Pseudochironomus ruah sp. n. Shimabukuro & Trivinho-Strixino

Type material. Holotype male BRAZIL, MG, PaSSa-Quatro, Pedra da Mina Mountain, Vale do Ruah, firSt order Stream, 22˚24'697''S 44˚50'930''W, 2575 m a.S.l., 14.x.2014, E.M. Shimabukuro, G. Perbiche-NeVeS & V.S. Saito (I1 – 15, LEIA-UFSCar). ParatypeS: three maleS (I1 – 16–18, LEIA-UFSCar), three femaleS (I1 – 19–21, LEIA- UFSCar), three pupal exuViae (I1 – 22–23, LEIA-UFSCar) and three larVae, Same data aS holotype, except for 5.Viii.2013 (I1 – 24, LEIA-UFSCar). Additional material examined: one male, one female and fiVe larVae, Same data aS holotype.

Etymology. Named after the type locality, Ruah Valley at Pedra da Mina mountain . The name iS treated aS a noun in appoSition.

Diagnostic characters. Adult male: total length 4.23–5.20 mm; wing length 3.0 0–3.34 mm; preSence of acroStichalS; TIX wide, with a notch, and oVerlapping approximately the half of inferior VolSella; gonoStyluS broad and Short; median VolSella enlarged and Somewhat flattened, preSenting one or more thin and long Setae; Superior VolSella without microtrichia, but preSenting one long Seta; parS VentraliS completely diVided; dark brown mark in tibial/femur connection. Female: thorax with dark brown markS; thorax with acroStichalS; cerci 174–245 µm long. Pupa: exuVia dark brown; thoracic horn 356–406 µm long; median and poSterior precornealS ariSing from an apparently tough protuberance; a pair of tubercleS on SI with few and SparSe SpineS; TI bare; TV-TVIII with thin D1 Setae; anal lobe with 28–33 double fringe of taeniate Setae. Larva: cephalic capSule dark brown, mentum, clawS of poSterior parapodS and mandible teeth, except apical tooth, black; mentum with 11 teeth; fiVe median teeth forming a conciSe and Somewhat iSolate group, the three median higher than the other teeth, and the Second lateral Very Small and fuSed with the firSt lateral; fifth and Sixth lateral teeth flattened and fuSed, SometimeS preSenting a Small fiSSure; baSal Segment of antenna Slightly Smaller than premandible; AR=1.41–1.89.

Adult male (n = 4)

Total length 4.23–5.20 mm. Wing 3.00– 3.34 mm long and 0.92–0.97 mm wide. Total length/wing length 1.27– 1.61. Wing length/length of profemur 2.29–2.88.

Colouration: Tergite brown with pale areaS in the inSertion of Setae; Sternite pale, except SVI-SVII, which are Similar to dorSal colouration pattern. Thorax pale with dark brown markS ( Fig. 1 a). Wing hyaline with yellow VeinS. FemurS yellow, tibiae and tarSi with light brown colouration. All legS with dark brown mark in tibial/femur connection.

Head. AR = 2.95–3.28. Antenna 988–1000 µm long. 13 flagellomereS. LaSt flagellomere 737–769 µm long (3); more than 20 temporal Setae. ClypeuS with 18–21 Setae. Palpomere lengthS (µm) 56–81; 81–113; 188–219, 250–278; 294–363. Third palpomere with a Slight fingerlike proceSS.

Thorax ( Fig. 1 a). AcroStichalS 5–9 (2), uniSerial ( Fig. 1 a); antepronotalS, in lateral poSition 8–10, Small; dorSocentralS 13–18 in a Single row, ariSing from pale areaS; prealarS 5–7; Scutellum with 26–30 Setae, irregularly diStributed in double row.

Wing. VR 1.10. Brachiolum with 1–3 Setae. R with 15–20 Setae. R1 with 5–9. R4+5 with 2–7 apical Setae. Squama with 26–32 Setae.

Legs. Tibial SpurS lengthS (µm): front 59–72, mid 81–100 and 81–106, hind 84–106 µm and 94–116. LengthS and proportionS of legS aS in Table 2.

Hypopygium ( Fig. 2 a). Tergite IX broad and long, poSterior margin with a median notch with 20–22 Setae ( Fig. 2 c), oVerlapping half of inferior VolSella ( Fig. 2 a). LateroSternite IX with 6–14 Setae. Phallapodeme 100–112 µm long. TranSVerSe Sternapodeme 89–121 µm long. Superior VolSella 114–138 µm long ( Fig. 2 b), apically concaVe, ending in two pointS, one 25 µm long and the other 9 µm long; without microtrichia, but with one long Seta; inferior VolSella foot Shaped 89–97 µm long and completely hairy, with microtrichia and long Setae; longeSt apical Setae 46 µm long; median VolSella flattened15–16 µm long bearing 1–4 apical Setae 26–40 µm, and 1 Setae aboVe median VolSella 31 µm long. All Setae on median VolSella long and thin. Gonocoxite 226–246 µm long. GonoStyluS broad and Short 145–208 µm long. HR = 1.1–1.6. ParS VentraliS completely diVided, 69–85 µm long and 9–17 µm wide lobeS ( Fig. 2 d).

Female (n = 3)

Total length 4.5–5.5 mm. Wing length 3.1–3.5 mm long and 1.0– 1.1 mm wide.

Colouration. Colour aS male.

Head. Antenna 403–447 µm long. AR 0.87–0.93. FiVe flagellomereS. LaSt flagellomere 215–231 µm long. TemporalS 30–32 (2). ClypeuS with 18–23 Setae. Length of palp SegmentS 2–5 (µm): 94–112; 144–225; 250–269; 350–375 (1). Slightly fingerlike proceSS on third palpomere.

Thorax chaetotaxy. AcroStichalS 2–5, uniSerial; antepronotalS, in lateral poSition 8–9; dorSocentralS 14–22; prealarS 6–7; ScutellarS 29.

Wing. VR 1.06–1.09. Brachiolum with 2 Setae. R with 22–25; R1 with 11–15; R4+5 with 21–36, lacking Seta proximally. Squama with 27–39 Setae.

Legs. Tibial Spur lengthS (µm) front 57–71; middle 86–93 and 92–105, hind 89–103 and 106–110. Length and LR proportion of legS aS in Table 3.

Genitalia: Gca VIII Strong, rounded poSteriorly. SVIII bearing 24–28 Setae irregularly diStributed at each Side. GPVIII 58–88 (2) µm long. Seminal capSule 128–146 µm. Notum 149–175 µm long. Gonocoxite IX 41 –61 µm long. PoStgenital plate 28–54 µm long. CercuS 174–245 µm long.

Pupa (n = 3)

Total length 4.83–5.83 mm. ExuViae dark brown.

Cephalotorax. Frontal Setae abSent. Thoracic horn ( Fig. 3 f) 356–406 µm long, Smooth. Three precornealS, median and poSterior ariSing from a tough protuberance ( Fig. 3 f); anterior precorneal 131–189 µm long, median precorneal 192–230 µm long and poSterior precorneal 65–111 µm long, median and poSterior ariSing from a tough protuberance; 2 antepronotalS, one with 172–223 µm and the other with 194–265 µm, 4 dorSocentralS, Dc1 69–92 µm long, Dc2 54–155 µm long, Dc3 108–123 µm long, Dc4 61–89 µm long, Dc1Separated from Dc2 by 35–46 µm; Dc3 Separated from Dc4 by 55–81 µm; and Dc2 from Dc4 by 528–578 µm.

Abdomen ( Fig. 3 a–b). Tergite I bare; TII–TVI coVered with Shagreen; TVII–TVIII with Shagreen only on anterior margin; SI with one pair of tubercleS with few and SparSe SpineS ( Fig. 3 c); TIII with anterior band of Strong SpinuleS. Hook row continuouS with about 67–90 curVed SpineS occupying near 1/3 width of Segment II. ConjunctiVeS III/IV to IV/V with 6 rowS of Sclerotized Spinulae. TV–TVIII with thin D1 Setae aS in figure 3e. PedeS Spurii A abSent. Segment VIII with poSterolateral comb, with 4–8 caudolateral SpineS ( Fig. 3 d); the longeSt Spine with 25–31 µm long. SegmentS II and III with one Small L Setae and one dorSolateral Setae. Segment IV with one L Seta. PedeS Spurii B preSent on Segment II and III. SegmentS V–VIII with 3, 4, 4, 5 taeniate Setae. Anal lobe 338–369 µm long, with 28–33 double fringe of taeniate Setae and a pair of dorSal Setae.

Larva (n = 3)

Colouration. Head dark brown; mentum, mandibular teeth except apical tooth black, clawS on parapodS Strong and black.

Head. Head 615–877 µm wide. Antenna with 5 SegmentS ( Fig. 4 c), length of antennal SegmentS (µm) 123–131; 28 (2); 17–21 (2); 11–14 (2); 6–9 (2). AR = 1.41–1.89. Antennal blade 69–89 (2) µm long. Lauterborn organ 8 (2) µm long. Premandible 140–181 µm long ( Fig. 4 g). Pecten epipharyngiS with 3 teeth ( Fig. 4 e), 8–18 (2) µm long and 14–23 µm wide. Mentum 246–277 µm long, with 11 teeth ( Fig. 4 a). FiVe median teeth forming a conciSe and Somewhat iSolate group, the three median higher than the other teeth and the Second lateral Very Small and fuSed with the firSt lateral. Fifth and Sixth lateral tooth Very flattened and fuSed, SometimeS preSenting a Small fiSSure. Mentum/head width: 0.28–0.45. DiStance between Submental Setae: 194–243 µm. Ventromental plateS 38–48 µm wide, touching each other at the midline. DorSal ScleriteS of head aS in figure 4b. Mandible 238–300 µm long ( Fig. 4 d) with a pale and Strong apical tooth and three black inner teeth.

Abdomen. Length 9–10 mm. ProcercuS with 6–8 Setae each ( Fig. 4 f). Anal Seta 656–712 µm long. SubbaSal Seta on procercuS 100–128 µm long. Anal tubuleS Short, 329–385 µm long. SubbaSal Seta on parapod 138–151 µm long. ParapodS clawS Strong.

Remarks. The adult maleS of P. ruah sp. n. reSemble the other new SpecieS by the preSence of acroStichalS, Superior VolSella without microtrichia and the parS VentraliS completely deVided. HoweVer, P. ruah sp. n. differS from itS congeneric by the larger body Size; by the Size and Shape of TIX, which iS longer and wider in P. ruah sp. n.; by the flattened median VolSella, bearing at leaSt one thin Seta; and by the preSence of only one Setae on Superior VolSella.

MoSt of the femaleS of Pseudochironomus remainS unknown or were not completely deScribed yet. A detailed deScription of Pseudochironomus fulviventris (JohanSen) iS giVen by Saether (1977), and although it preSentS Some SimilaritieS with P. ruah sp. n., they differ in colouration, Since P. ruah sp. n. preSentS dark brown thoracic marking and alSo preSentS few acroStichalS. They alSo differ in the Size of the cerci, Slightly Smaller in P. ruah sp. n..

Pupa of P. ruah sp. n. iS Similar to the P. richardsoni one due to the preSence of one pair of tubercleS in SI, the Same colouration and the number of caudolateral SpineS, but they differ in the Size of thoracic horn, which iS more than two timeS larger and diVided in two brancheS in P. richarsoni . AlSo, P. ruah sp. n. preSentS more than 15 taeniate Setae on anal lobe. The pupa of P. ruah sp. n. alSo reSembleS Pseudochironomus Spec. 1 deScribed by Wiedenbrug (2000), due to the preSence of a pair of tubercleS on SI, howeVer, Pseudochironomus Spec. 1 haVe no SpineS on tubercleS.

Regarding the format and the number of teeth in mentum, the larVae of P. ruah sp. n. are Similar to Pseudochironomus articaudus Saether, 1977 , but they differ by the AR ratio and the Size of baSal Segment of antenna, which are higher in P. ruah sp. n..

Ecological notes. Pseudochironomus ruah sp. n. adultS were collected with emergence trapS ( Shimabukuro et al. 2015) in marginal rockS of a Small mountain Stream, Situated at 2500 m. a.S.l. LarVae and pupae were collected right below where the trapS were Set. Although we tried to aSSociate immature and adultS uSing DNA barcoding, only SequenceS from adultS were good enough for the analySiS. HoweVer, we can confidently aSSociate larVae and pupae with adultS of P. ruah sp. n., due to the Sampling methodology (emergent adultS and encloSure immature inSide the trapS). The only SpecieS of Pseudochironomus that emerged in the trapS waS P. ruah sp. n., and further morphological analySiS of the immatureS reVealed the preSence of only one morphotype, preSumably the immatureS of P. ruah sp. n.. The water where immature waS collected waS cold and cryStalline; pH: 5.5 and diSSolVed oxygen: 7.4. The local Vegetation waS predominantly compoSed by natural Shrub and graSS field (CampoS de Altitude Vegetation).

DNA barcoding. COI barcodeS of ten adultS of Pseudochironomus ruah sp. n. haVe been SucceSSfully amplified and Sequenced, enabling the aSSociation between maleS and femaleS ( Fig. 5 ). All SpecieS of PSeudochironomini formed diStinct cluSterS in the NJ tree ( Fig. 5 ), and the fiVe cluSterS had itS BIN, Barcode Index Number ( RatnaSingham & Hebert 2013), compared. At the taxonomic leVel of genuS, Pseudochironomus SpecimenS did not cluSter together, forming 2 diStinct cluSterS and two unique SequenceS, repreSenting poSSibly 4 different SpecieS, including P. ruah sp. n.. The mean genetic diStance between both Pseudochironomus cluSterS (repreSented by BINS BOLD:ABD2966 and BOLD:AAG5477) waS 18.23%, which waS higher than between Pseudochironomus ruah sp. n. (BOLD:ABD2966) and Riethia Kieffer (BOLD:ACG1179—16.72%) and Slightly lower than P. ruah sp. n. and Manoa Fittkau (18.73%).

Maximum intraSpecific genetic diVergence baSed on K2P diStanceS were 0.15% for P. ruah sp. n. (BOLD:ABD2966) and Manoa xianjensis Qi & Lin, 2017 (BOLD:ADC2680), 1.35% for Pseudochironomus Sp. (BOLD:AAG5477) and 18.1% for Riethia stictoptera Kieffer, 1917 , howeVer aS already pointed out by Qi et al. (2017) it iS likely we are dealing with two diStinct taxa, in which different BINS haVe been already tentatiVely aSSigned (BOLD: AAJ4105 and BOLD:ACQ1179).

DNA Barcoding haS been uSed to confidently aSSociate chironomid aquatic life StageS (TriVinho-Strixino et al. 2012, TriVinho-Strixino & Pepinelli 2015) and here enabled the aSSociation between maleS and femaleS of P. ruah sp. n. and alSo aSSociated maleS, femaleS and larVa of Pseudochironomus Sp. , BIN BOLD:AAG5477, collected at different SiteS, Such aS maleS and femaleS from Manitoba and Ontario in Canada, and larVae apparently collected in the United StateS of America.

Figures

FIGURE 1. Thorax and detail of the acrostichals and setal scars on scutum, lateral vieW. a. Pseudochironomus ruah sp. n.. b. Pseudochironomus jordensis sp. n.. c. Pseudochironomus mocidade sp. n.. d. Pseudochironomus surianae sp. n..

FIGURE 2. Pseudochironomus ruah sp. n. adult male. a. hypopygium, left dorsal, right ventral vieW; b. superior volsella; c. posterior margin of tergite IX; d. pars ventralis.

FIGURE 3. Pseudochironomus ruah sp. n. pupa. a. abdomen, TI-TV b. abdomen, TVI-TVIII and anal lobe. c. tubercle from SI. d. posterolateral comb on segment VIII e. from left to right: D 1 setae from TV-TVIII. f. thorax, lateral vieW.

FIGURE 4. Pseudochironomus ruah sp. n. larva. a. mentum and ventromental plate. b. dorsal sclerites of head. c. antenna. d. mandible. e. pecten epipharyngis. f. last segment of abdomen (procercus, anal tubules and parapods). g. premandible.

FIGURE 5. Kimura 2 - parameter neighbor joining tree of Pseudochironomini taxa, including Pseudochironomus ruah sp. n..