A taxonomic revision of the genus Stempellinella (Diptera: Chironomidae) Author Ekrem, Torbjørn text Journal of Natural History 2007 2007-08-31 41 21 - 24 1367 1465 http://dx.doi.org/10.1080/00222930701437360 journal article 10.1080/00222930701437360 1464-5262 5229191 Stempellinella chambiensis (Goetghebuer) comb. n. Thienemanniella chambiensis Goetghebuer 1935 , p 52 . Lectotype „ (RMCA) Congo , Parc National Albert, Cratère Mufunga, 1933, De Wulf; 1 „ paralectotype , Congo , Escarpement Kabasha, Chambi, October 1933 , De Wulf (originally labelled as type of Thienemanniella trivittata ) [both examined]. Stempellina chambiensis (Goetghebuer) . Freeman (1958) lectotype designation, description, and distribution. Additional material examined Argentina ( ZSM ): 1 Pex , Prov. Missiones , INTA km 1272 near San Vincente , 1 November 1986 , E. Dominguez. Australia ( ZSM ): 1 „ , Queensland , Walsh River , 8 km E Dimbulah , light trap , 7–8 June 1993 , M. and B. Baehr ; 1 Pex, Queensland , Yabba Creek , 10 km NE Imbil , 21 November 1990 , M. Baehr. Brazil : 1 P( „ ), 3 Pex ( UFSC ) Brazil , São Paulo , São Carlos , Fazzari stream, May 2004 , July 2004 , T . Siqueira ; 1 „ , 1♀ , 1 Pex, 1 Lex, 4 L as previous, except 19 August 2002 , March 2003 , F. Roque ; 1 „ ( ZSM ) Amazonas , Rio Cuieiras , Igarape´ , 300 m below Cachoeira dos Indios, 29 July 1965 , E. J. Fittkau ; 4 Pex ( ZSM ) Amazonas , Chavantina Caximbu , Igarapé Vale dos Antas , 18 August 1965 , E. J. Fittkau ; 1 Pex ( ZSM ) Amazonas , Tiriyae , drift, 22–23 March 1962 , E. J. Fittkau ; LP ♀ , 1 Pex ( ZSM ) São Paulo State , São Carlos , stream on university campus, 30 November 1996 , F. Reiss and E. J. Fittkau ; 2 L ( ZSM ) Mato Grosso , Rio Bento Gomes , Campo Alegre , spring, 4 May 1993 , E. Stur ; 3 L as previous, except at Filisterra , 31 August 1993 ; 4 ( ZSM ) Pex , Rio Grande du Sul , Taquara , Arroio do Mineiro , 100 m a.s.l. , 12 March 1995 , S. Wiedenbrug ; 2 Pex as previous except cidade de Mato Leitão , Arroio do Sampaio , 400 m a.s.l. , 29 November 1994 . China ( ZSM ): 1 Pex , Yunnan Province , Tri Ping Fung , Mung Lun , 28 May 1980 , E. J. Fittkau. Congo ( RMCA ): 1♀ , Escarpement Kabasha , Chambi , October 1933 , De Wulf . Philippines ( ZSM ): 1 „ , Palawan , Babuyan River , light trap , 5–6 April 1995 , Cayasan, W . Mey . South Africa ( AMGS ): 3 „„ , 2♀♀ , Krüger National Park , Sabie River opposite Lisbon estate, 24 ° 599S, 31 ° 279E, 13 June 1986 . Diagnostic characters Stempellinella chambiensis can be separated from other Stempellinella species by the following combination of characters: male imago with AR ca 0.5; anal point long, thin, with comparatively low crests; base of anal point with two to four median tergite setae and numerous groups of three or four long microtrichia; lateral anal tergite seta present; median volsella medially directed, without microtrichia, with short, anally curved lamellae. Female imago with AR 0.25–0.30; VR 1.35–1.64; well-developed vaginal floor, covering ca onethird of vagina ventrally, with setae; cerci shorter than tergite IX; spermathecal ducts as long as notum (excluding rami). Pupa with strongly granulose frontal apotome and thorax; thoracic horn with numerous small but strong chaetae on distal two-thirds; hook row with ca 25 teeth; few but long points in patches on abdominal tergites III–VI; segment VIII with two (or sometimes three) lateral taeniate setae. Larva with large spur on antennal pedestal; AR lower than 0.8; antennal segment 5 as long as antennal segment 4; antennal blade extending far beyond apex of antennal segment 5; Lauterborn organs large with minute pedicels; premandible with three teeth; S3 split in three branches. Redescription Adult male ( n 5 6, unless otherwise stated). Total length 1.0–1.2, 1.1 mm ; wing length 0.70– 0.75, 0.74 mm . Colour: cleared specimens pale brown with somewhat darker scutal stripes and postnotum, eyes red with darker ventral margin. Head ( Figure 7A, B ): eyes without dorsomedian elongation; frontal tubercle small, 3–7, 5 Mm long; antenna with 12 flagellomeres of which only 10 are easily discernible; AR (on 10 flagellomeres) 0.48–0.50, 0.49 ( n 54); lengths of palpomeres ( n 52): 15–20, 15–20, 39–45, 59–65, 80–88. Clypeus about 40 Mm long with seven setae; tentorium ca 65 Mm long, 5 Mm wide; two inner verticals, one outer vertical, two postorbitals. Thorax: scutal tubercle absent; acrostichals 10–12, 11; dorsocentrals 4–5; humerals 1–2; prealars 1; scutellars 2–4; halterals 5. Wing ( Figure 7C ): cuneiform, 2.8–3.0 times longer than broad; VR 1.60–1.75, 1.67; wing setation as in Figure 7C . Legs ( Figure 7D ): fore tibia with 10–15, 13 Mm long spur; mid and hind tibiae with two well separated, 8 Mm long tibial combs, each with 17 Mm long spur; tarsi without sensilla chaetica; pulvilli absent. Lengths and ratios of leg segments in Table III. Hypopygium ( Figure 7E, F ): anal tergite 63–70 Mm long with transverse anal tergite band, two median setae close to anal point, one lateral seta, 14–18, 16 apical setae; anal point ca 30 Mm long, basally broad with low crests, distally thin and pointed; base of anal point with numerous groups of three to five long microtrichia which look like spinules under low magnification; minute microtrichia-free areas on either side of anal point. Gonocoxite 54–66, 58 Mm long; gonostylus 30–39, 35 Mm long; HR 1.46– 1.83, 1.68. Superior volsella ( Figure 7F ) oval, medially directed with four dorsal and three median setae on setiger, otherwise bare; digitus absent; median volsella ca 30 Mm long, medially directed, without microtrichia, with fan of 15 Mm long, anally directed lamellae; inferior volsella ca 40 Mm long, slightly club-shaped, with several distal setae. Adult female ( n 5 4, unless otherwise stated) tentatively associated. Total length 1.0–1.2, 1.1 ( n 53); wing length 0.59–0.80, 0.71. Colour: as male. Head: as male, except antenna ( Figure 7G ) with five flagellomeres, ultimate flagellomere 36–40, 39 Mm long, AR 0.25–0.29, 0.27; lengths of palpomeres (in Mm): 10–20, 15; 15–20, 18; 30–40, 35; 45–57, 53; 73–85, 77. Clypeus with seven to nine setae. Thorax: as male, except humerals sometimes absent. Wing: as male, except VR somewhat lower 1.35–1.64, 1.52. Legs: as male except combs and spurs 2–3 Mm longer. Genitalia ( Figure 7H ): tergite IX slightly triangular, about 45 Mm long; sternite VIII with 12–14 setae, of which three or four are placed on vaginal floor; vaginal floor well developed covering ca one-third of vagina ventrally; gonapophysis VIII single lobe with long medially directed microtrichia; gonocoxapodeme slightly curved; coxosternapodeme well developed with large lateral lobe. Notum including rami 90–105, 97 Mm long, notum alone ca 65 Mm long. Seminal capsules ovoid, diameter 30–36, 32 Mm with 60–75, 67 ( n 53) Mm long spermathecal ducts. Postgenital plate subtriangular. Cercus 24–27, 25 Mm long. Pupa ( n 5 5, unless otherwise stated). Total length 1.6–1.7 mm ; abdomen 1.2–1.3 mm long. Colour of pupal exuviae brown with somewhat darker cephalothorax and lateral margins on abdominal segments V–IX, transverse brown pigmented band posteriorly on segment VIII. Figure 7. Stempellinella chambiensis (Goetghebuer) , imagines. (A–F) Male: (A) head; (B) antennal flagellum; (C) wing; (D) fore, mid, and hind tibiae; (E) hypopygium; (F) superior and median volsellae. (G, H) Female: (G) antenna; (H) genitalia. Cephalothorax ( Figure 8A, B ): cephalic tubercle well-developed cones, 18–24, 22 Mm long; frontal setae taeniate, 150–200, 179 ( n 54) Mm long; pedicel sheath tubercle absent. Frontal apotome with strong granulation ( Figure 8A ). Thoracic horn 200–285, 234 Mm long, 15–24, 18 Mm wide with numerous 6 Mm long chaetae on distal two-thirds of horn; precorneals taeniate, 150–210, 180 Mm long, arranged in a triangular pattern on small tubercles; median antepronotal taeniate on obvious tubercle, ca 180 Mm long, two lateral antepronotals: one taeniate, ca 100 Mm long, one sensillum basiconicum; two pairs of fine dorsocentrals, anterior pair somewhat longer than posterior pair (30–45, 38 Mm). Large area of granulation and fine wrinkles on thorax ( Figure 8B ), a few stronger granules present along median suture line. Prealar tubercle well developed, wide; nose of wing sheath strong, triangular. Abdomen ( Figure 8C ): TII with minute, semicircular posteromedian point patch; hook row 45–55, 51 Mm wide with 22–30, 25 hooks. TIII–VI with point patches which are partly divided longitudinally, patches on TV–VI often also transversely divided in middle; TVI– IX with anterolateral patches of shagreen; pleurae on segment IV–V with weak shagreen. Segment II with pedes spurii B; segment IV with pedes spurii A. Segment II with 2 D, 2 V, 3 L setae; segment III with 3 D, 2–3 V, 1–2 L, 1–2 taeniate L setae; segment IV with 3 D, 2–3 V, 1–2 L, 1–2 taeniate L setae; segment V with 2 D, 2–3 V, 3 taeniate L setae; segment VI with 2 D, 2–3 V, 4 taeniate L setae; segment VII with 3 D, 2–3 V, 4 taeniate L setae; segment VIII with 1 D, 1 semi-taeniate V, 2 taeniate L setae (three taeniae in the Australian, Chinese, and five Brazilian specimens); segment IX with 1 taeniate D seta on anal lobe, 11–16, 14 ( n 56) taeniate setae in anal fringe. One pair of O-setae present anteriorly on tergites II–VIII and anterolaterally on sternites II–VIII. Posterolateral spur on segment VIII well developed. Larva ( n 5 5, unless otherwise stated). Total length ca 1.3 mm , case ca 1.7 mm . Head capsule pale brown, somewhat darker postoccipital rim and teeth on mandible and mentum. Live individuals not examined. Head ( Figure 8D–I ): head capsule length 155–180, 165 Mm. AR 0.66–0.75, 0.72; antennal pedestal 39–48, 45 Mm long with well-developed, 18–22, 21 Mm digitiform spur; antenna ( Figure 8D ) with all segments well sclerotized, segment lengths (in Mm): 42–45, 44; 30–36, 34; 10–12, 11; 10–12, 12; 4–6, 5; segment 3 inserted very slightly subapical on segment 2; AAR 0.93–1.14, 1.03. Antennal seta placed at base just above ring organ; antennal blade ca 80 Mm long, pale, reaching well beyond tip of apical Lauterborn organ; peg of antennal segment 2 placed subapically on segment. Lauterborn organs large, bulbous, 18–21, 19 Mm long; both organs on 2–3 Mm long pedicel; SII and chaetae pectinate, chaetulae simple; S3 usually split in three branches ( Figure 8E ); pecten epipharyngis consists of three well-developed, pointed chaetae; labral lamella with 22–26 ( n 53) teeth. Mentum ( Figure 8F ) with 13 teeth, median tooth with obvious lateral notches, somewhat paler, first lateral tooth set closer to median tooth than to second lateral tooth; ventromental plates medially barely reaching third lateral tooth of mentum, MVR ca 1.2; premandible ( Figure 8G ) with three teeth, well-developed brush; mandible ( Figure 6H ) with pecten mandibularis slightly convex, seta subdentalis 30 Mm long; postoccipital plate ( Figure 8I ) well developed, split. Body: anterior parapods with long, simple spines; hind parapods with 14–20, 15 simple hooks; L2 apparently simple; anal segment with four narrow anal tubules, ca 65 Mm long; supraanal seta strong, ca 220 Mm long; procercus ca 15 Mm long with two short (ca 100 Mm long) and four long (ca 470 Mm long) anal setae, the short setae situated individually, and not on the common base of the long setae. Remarks As Freeman (1958 , p 353) noted, several of the syntypes belonging to Thienemanniella chambiensis and T. trivittata must have been wrongly labelled at some point. I largely agree with Freeman’s (1956 , 1958 ) decision in designing and sorting the true types, with the exception that I will not regard the female, but the male from Kabasha as paralectotype . The female specimen is not included in Goetghebuer’s (1935 , p 52) original description, but the male is and should be regarded as belonging to the original type series. I have also examined the two additional specimens listed by Freeman, one male from Amadi, Sudan and one male from Nelspruit in Transvaal. Neither of these is conspecific with Stempellinella chambiensis , and both fit the diagnosis of Stempellina given in Cranston et al. (1989) . Figure 8. Stempellinella chambiensis (Goetghebuer) , immatures. (A–C) Pupa: (A) frontal apotome; (B) thorax; (C) abdomen, dorsal view. (D–I) Larva: (D) antenna; (E) clypal seta S3; (F) mentum and ventromental plates; (G) premandible; (H) mandible; (I) postoccipital plate. Males of Stempellinella chambiensis are quite similar to the males of the Palaearctic S. edwardsi , the Japanese S. coronata , and the Neotropic S. lamellata , but can be separated from all these species by the above combination of diagnostic characters. The pupal exuviae are perhaps most similar to those of S. leptocelloides , but can be separated from these by the more granulose frontal apotome and thorax, and the shorter frontal tubercles. The species has so far been recorded from Africa, Southeast Asia, Australia , and South America typically in and along slow-flowing rivers and streams with a pH of around 7. The Tri Ping Fung area ( China ) was at the time of sampling a small primary forest on limestone formations. The river water was clear and the river bank was lined with large boulders and coarse gravel (E. J. Fittkau, personal communication). Stempellinella chambiensis larvae were quite numerous in sandy and stony parts of the Rio Bento Gomes ( Stempellinella in Stur 2000 ), and occurred at the spring as well as in the fourthorder stream. The Rio Bento Gomes shows large seasonal fluctuations in the water level, and S. chambiensis appeared to be most numerous in periods of reduced water flow at the end of August ( Stur 2000 ). The two Australian localities where S. chambiensis has been sampled are quite different. The stream in Yabba Creek north of Brisbane is small and shaded, while Walsh River east of Dimbulah lays in a more tropical, dry area and has less vegetation lining its banks (M. Baehr, personal communication). The Fazzari stream in São Paulo State , Brazil is a first-order stream surrounded by a well-preserved riparian forest. The water has a high level of dissolved oxygen, low conductivity, and temperatures ranging from 15 to 21 ° C, while the stream bed is characterized by a predominance of organic material in the bottom substrate (F. Roque, personal communication). The larvae of S. chambiensis build small transportable cases of sand grains and organic particles as in the remainder of the species in the genus. Compared with the other species in Stempellinella , S. chambiensis has an extraordinarily wide distribution. Thus, it is tempting to question the conspecificity of the sampled populations. However, I have not been able to observe any morphological differences between the sampled specimens large enough to be diagnostic, and therefore choose to treat the examined specimens as one species until observed genetic variation between the geographically separate populations proves otherwise.