Thienemanniella trivittata Goetghebuer

Abstract

<i>Thienemanniella trivittata</i> Goetghebuer <p>(Figs 6 A–M; Figs 7 A–E)</p> <p> <b>Material examined.</b> SOUTH AFRICA: Cape Province, French Hoek, 1 3, 5 ƤƤ, 22.x.1952, K. M. F Scott; paratypes of <i>T. analis</i> Freeman (BMNH). Cape Province, Wellington, Berg River, 1 3 and 1 Ƥ, 28.ix.1953, K. M. F. Scott (BMNH). Natal, Bushman`s River, Giant`s Castle Camp, 1 3, 14 –30.ix.1953, A. D. Harrison (BMNH).</p> <p> <b>Diagnostic characters.</b> The species is separable from all other Afrotropical members of the genus except <i>T. cavata</i> <b>sp. n.</b> by having two outer verticals. However, it differs in having two ventrolateral patches of 4–6 (male) and 3–4 (female) setae on tergite I. Both male and female imagines have wings with well developed anal lobe. The adult male has 12 flagellomeres and a small inferior volsella with apodeme. The adult female has a well developed tergite IX with about 18 caudal setae, rami slightly broadened into oval shape, and each gonocoxapodeme split both orally and caudally.</p> <p>Adult male (n = 4)</p> <p>Total length 1.34–1.45 mm. Wing length 0.80–0.98 mm. Wing width/wing length 0.38–0.42 (2). Total length/wing length 1.48–1.71. Wing length/ length of profemur 2.93–3.71.</p> <p> <i>Coloration</i>. As in Freeman, 1956, but paler due to long time storage on needles prior to slide preparation.</p> <p> <i>Head</i> (Figs 6 A–C). Eyes hairy; height of eye/height of head 0.56–0.62. AR 0.21–0.28. Antenna with 12 flagellomeres; length of ultimate flagellomere equals preceding 2.5–3, flagellum apically club-shaped, with maximum width 21–28 µm. Ultimate flagellomere apically rounded or notched with numerous apical sensilla chaetica situated from 0.67–0.72 of segment to apex, and 10–16 basal setae at inner part. Tentorium, stipes and cibarial pump as in Fig. 6 C; tentorium 134–191 µm long, stipes 72–102 µm long. Palpomere lengths (in µm): 18–25, 15–22, 33–40, 44–58, 102–109. Palpomere 5/3 3.0–3.2; palpomere 3 elliptical, apically thicker then inner part. Sensilla clavata lacking. Clypeus with 9–13 setae. Outer verticals 2, coronals 4.</p> <p> <i>Thorax</i> (Fig. 6 D). Anapleural suture 126–149 (3) µm long, s/a 0.58–0.65 (2). Antepronotals 2 (not show in the figure), dorsocentrals 10–20, uniserial, bi- or triserial anterior, uniserial posterior; prealars 3–4, scutellars 3–6.</p> <p> <i>Wing</i> (Fig. 6 E). VR 1.67–1.87 (3). Two anal veins present, An2/wing length 0.13–0.16 (2), An1/wing length 0.43–0.52 (3). PCu/wing length 0.53–0.59 (3), Cu 379–508 (3) µm long, Cu/wing length 0.44–0.51 (3), C 301–347 (3) µm long, C/wing length 0.34–0.35 (3). Costal margin with 14–21, 18 uniserial setae, remaining anterior margin with shorter strong seta, posterior wing margin with alternating long and short hair-like setae.</p> <p> <i>Legs.</i> Fore trochanter without keel. Spur of fore tibia 21–26 (3) µm long, serrated. Mid tibia with 3 spurs, 9–13 µm, 13–16 µm and 20–21 (3) µm long. Hind tibia (Fig. 5 F) with strong simple spur 26–27 (2) µm long and strong seta 15–20 (3) µm long. Apex of fore tibia 25–26 (3) µm wide, of mid tibia 24–31 (3) µm wide, of hind tibia (a) 37–39 (2) µm wide. Width of hind tibia 1/3 from apex (d) 27–31 (2) µm, elongation length (b) 16–18 (2) µm, length of maximum thickening (c1) 34 (2) µm, total length of thickening (c2) 48–57 (2) µm; a/d 1.25–1.37 (2); b/d 0.51–0.66 (2); c1/d 1.10–1.26 (2); c2/d 1.77–1.84 (2). Hind tibial comb of 16 (2) setae. Sensilla chaetica absent. Ta1 of foreleg with ventral row of 7–8 (2) strong setae, ta2 with dorsal row of 6 (1) strong setae, ta2 and ta3 with 1 strong seta apically. Ta1 of midleg with ventral row of 11 (2) strong setae, ta2 with ventral row of 5–6 (2) strong setae, ta3 and ta4 with inwards curved seta to each side apically. Ta1 of hind leg with a ventral row of 9–12 (2) strong setae and anteroventral row of 9–10 strong setae, ta2 with 4 (1) ventral and 1 apical strong setae, ta3 with 1 ventral and 1 apical strong seta, ta4 with 2 apical setae. Lengths (in µm) and proportions of legs as in Table 8.</p> <p> <i>Abdomen</i> (Fig. 6 G). Tergite VI and VII with median pale field. Tergite I with 4–6 setae laterally on each side. Number of setae of tergites II–VII: 7–8, 7–8, 6–8, 6–7, 9, 7. Tergite VIII with 1 seta on each side, 0–2 medially, sternites bare.</p> <p> <i>Hypopygium</i> (Fig. 6 H). Sternite VIII bare, tergite IX with numerous small setae, laterosternites IX with 1 seta. Gonocoxite IX with 9–15 strong setae dorsally and laterally, 2–5 smaller, glandular setae on ventral surface, inner margin with long thin glandular setae. Superior volsella narrow, anteriomedially fused, posteriorly in contact with inferior volsella by thin apodeme. Superior volsella partly subdivided in anterior and posterior part. Inferior volsella small, pointed triangular edge medially with apodeme, about 5 µm wide, is protruding over phallapodeme. Phallapodeme strongly curved, length 47–66 µm, with lateral projections. Transverse sternapodeme narrow and very thin 20–25 µm, lateral sternapodeme 35–52 µm long. Gonocoxite 97–127 µm long. Gonostylus 36–46 µm long, stout megaseta 6–7 µm long. HR 2.30–2.95, HV 3.04–3.77.</p> <p>Adult female (n = 5–6)</p> <p>Total length 1.01–1.45, 1.32 mm. Wing length 0.79–0.95, 0.88 mm. Wing width/wing length 0.44–0.48, 0.46. Total length/wing length 1.32–1.71, 1.49. Wing length/profemur length 3.15–4.01, 3.51.</p> <p> <i>Coloration.</i> As in Freeman (1956).</p> <p> <i>Head</i> (Fig. 7 A). Eyes hairy. Height of eye/height of head 0.56–0.77, 0.65. AR 0.41–0.46. Length of flagellomeres (in µm): 33–42, 38; 33–38, 35; 35–44, 38; 31–33, 32; 59–63, 61. Ultimate flagellomere with 18–26, 22 apical sensilla chaetica, no basal setae. Tentorium 111–128, 120 µm long, stipes 70–111, 97 (3) µm long. Palpomere lengths (in µm): 15–18, 16; 18–22, 20; 29–36, 33; 29–51, 43; 98–117, 107. Palpomere 5/3 ratio: 2.7–4.0, 3.3; palpomere 3 elliptical to rectangular, apparently no sensilla clavata. Clypeus with 11–14, 13 setae. Outer verticals 2, coronals 4.</p> <p> <i>Thorax</i> (Fig. 7 C). Anapleural suture 128–154, 141 µm long, s/a 0.51–0.64, 0.57 Dorsocentrals 16–24, 21, tri- or bi serial anteriorly, uniserial posteriorly; prealars 4–7, 4; scutellars 3–9, 4.</p> <p> <i>Wing</i> (Fig. 7 B). VR 1.50–1.63, 1.56. Two anal veins present, An2/wing length 0.11–0.15, 0.13; An1/wing length 0.37–0.44, 0.41; PCu/wing length 0.51–0.63, 0.55; Cu 333–417, 388 µm long, Cu/wing length 0.42– 0.44, 0.44; C 389–514, 472 µm long; C/wing length 0.49–0.55, 0.53. Costa with 39–47, 43 marginal setae biserial distally, uniserial basally, other wing margin setation as for male.</p> <p> <i>Legs.</i> Fore trochanter without keel. Fore tibial spur serrated, 17–23 (3) µm long. Mid tibia spurs 15–20, 18 (4) µm and 14–16, 15 (4) µm long. Hind tibial spur, simple 30–43, 36 (5) µm long, lateral spur 17–20 (3) µm and a strong seta, 16–20 (2) µm long, slightly medially curved at tip. Fore tibial apex 25–32, 30 µm wide, mid tibia 26–43, 32 µm, hind tibia (a) 34–40, 38 µm. Width of hind tibia 1/3 from apex (d) 26–38, 32 µm, elongation length (b) 21–25, 23 µm, length of maximum thickening (c1) 36–40, 38 µm, total length of thickening (c2) 55–64, 58 µm; a/d 1.00–1.31, 1.17; b/d 0.58–0.85, 0.70; c1/d 0.95–1.38, 1.18; c2/d 1.25–2.11, 1.67. Hind tibial comb with 15 (3) setae. Sensilla chaetica on ta1 of midleg and ta1 and ta2 of hind leg. Mid leg: 9–10 at 0.27–0.29 to 0.85 (3) of leg, and hind leg: 7–8 at 0.40–0.45 to 0.79–0.85 of ta1, and 5–7 at 0.17–0.28 to 0.89–1.0 of ta2. Ta1 of foreleg with a ventral row of 7–8 (2) strong setae, ta2 with dorsal row of 4–6 (2) strong setae, ta2 and ta3 with 1 strong setae apically. Ta1 of midleg with ventral row of 8–10 (2) strong setae and 2 apical, strong setae, ta3 with ventral row of 4–6 (2) stiff setae. Ta1 of hind leg with a ventral row of 9–12, 11 strong setae, ta2 with 2 apical, slight inwards curved setae and 1 strong seta subapically, ta3 with 2 strong ventral setae and 1 apical strong setae, ta4 with 1 ventral setae at middle. Tarsomere 4 slightly cordiform. Lengths (in µm) and proportions of legs as in Table 9.</p> <p>fe ti ta1 ta2 ta3 ta4</p> <p>p1 201–306, 256 237–305, 277 157–211, 195 51–113, 76 26–51, 41 15–28, 20 p2 273–390, 326 259–333, 299 182–226, 198 73–106, 91 33–68, 45 15–46, 23 p</p> <p>3</p> <p>255–361, 310 277–379, 339 179–248, 205 102–138, 120 33–54, 41 15–28, 19</p> <p>ta5 LR BV SV BR</p> <p>p 1 28–37, 32 0.58–0.75, 0.68 3.53–4.70, 4.16 2.76–3.32, 2.87 1.2–2.4, 1.4 p 2 28–40, 33 0.58–0.74, 0.67 3.67–4.79, 4.17 2.92–3.95, 3.10 1.0–2.8, 1.7 p 3 27–33, 31 0.48–0.68, 0.61 3.53–4.95, 3.93 2.86–3.95, 3.18 2.0–3.0, 2.3</p> <p> <i>Abdomen.</i> Abdomen broad. Tergite I with 3–4 setae on each side. Number of setae on tergites II–VIII as: 7–8, 5–9, 5–9, 7–9, 8, 5–6. No setae on sternites.</p> <p> <i>Genitalia</i> (Figs 7 D–E). Gonapophysis VIII possibly subdivided mesally with parts in contact, more laterally and posteriorly a lobe or flap in contact with postgenital lobe externally covered with fine hairshaped microtrichia. Labia is a pair of very thin small lobes covered by ventrolateral lobes, below the spermathecal eminence. Postgenital lobe externally covered with spine-like microtrichia, hinged to segment X posteriorly making a flexible lid for the vaginal structures. Membrane thin, Y-shaped, situated anterior of spermathecal eminence, with cavity in basal portion for seminal ducts. Separate eminence for each seminal duct. Sternite VIII with 0 setae, tergite IX well developed, with 16–19, 18 setae all caudally and dorsally situated on small humps, gonocoxite IX with 2 setae. Internally and somewhat anterior of postgenital lobe a large heart-shaped bursa, possible subdivided in two, with finely thin sclerotized walls. Sclerotized rami are supporting the walls of this bursa. The cavity between gonapophysis VIII and labia is thus forming a copulatory bursa, anteriorly connected by sclerotized vagina to the openings of the spermathecal eminence. Gonocoxapodeme straight, narrow medially broader laterally. Coxosternapodeme split anteriorly, connected to rami and more posterior and dorsally to the apodeme of possible egg-chamber; posterior and more laterally supporting the gonocoxite. Cercus 39–54, 44 µm long. Notum length 52–91, 63 µm long. Seminal capsules 45–67, 54 µm long, 23–33, 26 µm wide.</p> <p> <b>Distribution.</b> The species is known from Cape Province, Natal and Transvaal in South Africa and the Democratic Republic of the Congo in Africa. It is also known from Australia (Freeman & Cranston, 1980).</p> <p> <b>Remarks.</b> Inferior volsella with an apodeme is also seen in the Nearctic species <i>T. lobapodema</i> and <i>T. antennata</i> although of a different type. The very clear and beautiful female specimens provided the opportunity to assess the fine structures of the genitalia in more detail than in previous studies. The large sclerotized bursa, possible for egg-storage, corresponds to a similar structure in <i>Corynoneura</i>. The arrangement of the labia and spermathecal eminence is quite similar to what is the case for <i>Heterotrissocladius hirtapex</i> Saether (1977, Fig 55: E).</p> <p> <b>Concluding remarks</b>. The Afrotropical males of <i>Thienemanniella</i> (and <i>Onconeura</i>) can easily be separated from <i>Corynoneura</i> by the shape of the transverse sternapodeme, straight or weakly U-shaped in <i>Thienemanniella</i> and Y-shaped or strongly U shaped in <i>Corynoneura</i>.</p> <p> The cavity in the gonocoxite in <i>T. cavata</i> is not seen in other <i>Thienemanniella</i> or related genera.</p> <p> The structure referred to as the superior volsella seems to be homologous within <i>Thienemanniella</i>, always appearing as a thin sclerotized plate or plates, grayish, yellowish or more hyaline, in the area caudal to the transverse sternapodeme. In some species it is divided into two lobes (e.g. <i>T. safi</i>), but in others it is joined anteriorly as seen in most of the species. In <i>T. safi</i>, according to Lehmann (1979) and <i>T. cavata</i> the lower edge of the superior volsella is more sclerotized and apodeme like. These plates seem to have the same appearance as the anterior directed plate of the phallapodeme in other orthoclad genera, suggesting a possible origin of this structure. It is tempting to suggest that the plesiomorphous state for this character is the divided plate.</p> <p> Inferior volsella is most often seen as a basal lobe of the gonocoxite (<i>T. lineola</i>, <i>T. fuga</i>), sometimes this lobe is situated more caudally, larger as in <i>T. majuscula</i> Edwards (Palaearctic) and the Neotropical <i>T. liae</i> Paggi (Paggi 2007: 247). <i>T. trivittata</i> and <i>T. antennata</i> have an inferior volsella with internal apodeme and without any setae. <i>T. lobapodema</i> from the Nearctic region and <i>T. antennata</i> are unique in the digitiform inferior volsella and other features thus suggesting a close relationship in phylogeny.</p> <p>Harrison (1992) argues that the presence of clavus is an adaptation to minute size. This view can possibly be supported by novelties in the collections of the Museum of Zoology, Bergen. Of importance for the future phylogenetic analysis of the group is especially the knowledge of the female genital structure, which analyzed under advanced microscopic techniques will provide many valuable characters. The presence of an eggchamber is not known from chironomids before. Also more data from larvae and pupae of the species will provide information for phylogenetic analysis of the genera and species relationships.</p> <p> The small size and reduced chaetotaxy, and loss of antennal flagellomeres have been suggested as adaptations to tropical climate (Saether 1996, Saether & Andersen 1996). Five of the six Afrotropical species have an antennal ratio lower than 0.30, three have a wing length lower than 0.70 mm, and four species have 8– 10 flagellomeres, all lower or less than the known Western Palaearctic and Nearctic species of <i>Thienemanniella</i> (Goetghebuer & Lenz 1935, Schlee 1968, Hestenes & Saether 2000).</p>Published as part of <i>Fu, Yue, Hestenes, Tor Christian & Saether, Ole, 2010, Review of Afrotropical Thienemanniella Kieffer (Diptera: Chironomidae: Orthocladiinae), pp. 1-22 in Zootaxa 2338</i> on pages 15-20, DOI: <a href="http://zenodo.org/record/193239">10.5281/zenodo.193239</a&gt