Tanytarsus lulu, Dantas & Amat & Hamada & Giłka, 2022

Dantas, Galileu P. S., Amat, Eduardo, Hamada, Neusa & Giłka, Wojciech, 2022, Towards the systematics and diversity of Neotropical Tanytarsus van der Wulp (Diptera: Chironomidae): news from Colombia, Zootaxa 5129 (4), pp. 505-529 : 515-517

Tanytarsus lulu sp. nov.

LSID: urn:lsid:zoobank.org:act:0FFBC66B-AF75-4301-ACA1-96195E22440C

( Fig. 5A–E )

Type material. Holotype, adult male: COLOMBIA, Meta Department, Puerto Lopez , 04º08’11’’N 72º52’53’’W, 206 m a.s.l., 01–03 January 2021, Malaise trap, G.P.S. Dantas, S.M. R. Hernández (CETdeA) . Paratypes: 1 male, same data as for holotype .

Derivatio nominis. The name is a tribute to the couple, Luz Helena Rangel and Luiz M. Hernández, for their invaluable help during fieldwork in Puerto Lopez, and especially for all the support and warm welcome given during the first author’s stay in Colombia. The specific epithet is formed by the junction of the first syllable of Luz and Luiz ( lulu ) and should be considered a noun in apposition.

Diagnosis. AR> 1. Frontal tubercles well-developed, over two times as long as wide. Mid leg with apical row of 4–7 sensilla chaetica. Tergite IX with lateral teeth. Orolateral spines of laterosternite IX in shape of small processes. Anal point with apex spoon-shaped, smooth, lacking serrations. Superior volsella oval, with posteromedian corner slightly projecting rounded, median margin slightly concave. Digitus pointed, extending slightly beyond median margin of superior volsella. Median volsella with 2–3 setiform and 3 pectinate lamellae. Inferior volsella with angular dorsal protrusion.

Description. Adult male (n = 2).

Body size and proportions. Total length 2.34–2.86 mm. Wing length 1.22–1.46 mm. Total length/wing length ratio 1.92–1.96. Wing length/length of profemur ratio 2.14–2.26.

Colouration. Eyes black. Antenna brown. Head capsule and thorax yellow to light brown. Legs: proximal half of femora pale, distal half of femora plus tibiae and tarsi light brown. Wing veins yellowish brown, membrane pale. Abdomen yellowish.

Head. Eyes bare, with moderately developed dorsomedian extensions. Antenna with 13 flagellomeres; ultimate flagellomere 425 μm long; AR 1.04. Frontal tubercles well-developed, 27–29 μm long, 12–15 μm wide, ca. 2.2 times as long as wide. Tentorium 140 μm long. Temporal setae 8–9 on each side. Clypeus with 17–18 setae. Lengths of palpomeres 1–5 (in μm): 26–27, 26–27, 67–80, 84–106, 153–169; third palpomere with 1 subapical sensillum clavatum 14 μm long.

Thorax. Ac 12, restricted to anterior region of scutum; Dc 6–7 on each side, uniserial; Pa 1 on each side; Scts 4. Scutum projected and rounded anteriorly, overreaching antepronotum. Halteres with at least 4 setae.

Wing. Somewhat oblong, with anal lobe reduced. Brachiolum with 1 seta, Sc bare, R with 16–18 setae, R 1 with 13–20 setae, R 4+5 with 11–18 setae, M bare, M 1+2 with 35–40 setae, M 3+4 with 30 setae, Cu with 4 setae, Cu 1 with 7–12 setae, postcubitus with 3–4 setae, An with 13–20 setae. Cell m bare (false vein bare), r 4+5 with 75–80 setae, m 1+2 with 70–80 setae (+48 setae on false vein), m 3+4 with 20–28 setae, cu and an bare. VRCu 1.20–1.23.

Legs. Foreleg tibia with short lanceolate spur 15–20 μm long. Lengths of combs of mid tibia 8–9 μm (with 11–12 μm long spur) and 13–17 μm (with 15–21 μm long spur); lengths of combs of hind tibia 14–15 μm (with 17–18 μm spur) and 17–19 μm (with 22–25 μm long spur). Basitarsus of mid leg with apical row of 4–7 sensilla chaetica. Lengths and proportions of legs as in Table 4.

Hypopygium. Tergite IX covered with microtrichia except for small bare area at base of anal point; lateral teeth present; orolateral spines of laterosternite IX in shape of small processes; anal tergite bands T-type, fused on median part of tergite, ending close to anal point base ( Fig. 5A, B ). Anal point 35–40 μm long, elongate, with spoon-shaped apex with margin smooth (without serrations), pair of dorsal setae at base, two lateral setae on each side and pair of ventral setae subapically; microtrichia and spinulae absent ( Fig. 5A, C ). Superior volsella 32–35 μm long, oval, posteromedian corner slightly projecting and rounded, median margin slightly concave; 6–7 setae on dorsal surface, 2 setae on median margin, and 1 ventral seta; field of microtrichia on dorsal surface absent; digitus 21–23 μm long, pointed, slightly extending beyond median margin of superior volsella ( Fig. 5A, B, D ). Stem of median volsella 13–15 μm long, with 2–3 setiform and 3 pectinate lamellae ( Fig. 5B, E ). Inferior volsella 75 μm long, covered with microtrichia, slightly curved and posteromedially directed, apex with angular dorsal protrusion. Phallapodeme ~100–105 μm long, strongly sinuous; transverse sternapodeme ~35–50 μm long, with well-developed oral projections. Gonocoxite 85–100 μm long. Gonostylus 125 μm long, narrow, slightly curved, tapering towards pointed apex. HR 0.80. HV 2.29.

Distribution and ecological notes. The adult male specimens examined were collected together with those of three other species described in the present paper. For details on ecology and bionomics see notes under Tanytarsus colombiensis .

Discussion. Tanytarsus lulu and several Neotropical species, i.e. T. ligulatus , T. paraligulatus as well as “ Tanytarsus cf. ligulatus ” [pre-named and described by Sanseverino (2006), but finally not delimited as new species nor yet validated] are distinct by the anal point crests forming an extraordinary structure—the round, spoon-shaped apex (cf. Reiss 1972, Sanseverino 2006). This character state prompted us to treat it as a main apomorphy for the ligulatus species group, proposed here. Several other diagnostic characters in common among the species mentioned above support this concept. All species analysed have well-developed, long frontal tubercles. They are 3.5 times as long as wide in T. ligulatus and T. cf. ligulatus , the ratio is 4 in T. paraligulatus , while 2.2 in T. lulu . In the ligulatus group, the superior volsella is more or less heart-shaped, with the median margin concave slightly at least (strongly concave in T. ligulatus and T. cf. ligulatus , nearly straight in T. paraligulatus , slightly concave in T. lulu ). The key character within the ligulatus group is also the size of the digitus, well-developed in all the species. However, T. lulu has the digitus pointed, extending slightly beyond the median margin of the superior volsella, while the digitus is finger-like, rounded apically, extending well beyond the superior volsella in T. ligulatus and T. paraligulatus . In this character T. lulu is similar to T. cf. ligulatus . These two, possibly the closest species share also some other features that differentiate them from both T. ligulatus and T. paraligulatus : the spoon-shaped anal point apex is round and have no serrations (teeth) on margin in T. lulu and T. cf. ligulatus , while the apex is flattened, with margin toothed in T. ligulatus and T. paraligulatus . Despite the aforementioned similarities, T. lulu and T. cf. ligulatus display several differences: the AR is greater than 1 (1.04) in T. lulu , while less than 1 (0.84) in T. cf. ligulatus ; other differentiate characters pertain to the frontal tubercle length/width ratio, the shape of the superior volsella (see above) and the wing chaetotaxy and macrotrichia—numerous in T. lulu relative to T. cf. ligulatus (cf. Sanseverino 2006). The structure of an auxiliary importance in the male Tanytarsini diagnostics are the hypopygial anterolateral teeth or orolateral spines of laterosternite IX, however, they usually are minute thus weakly observable. The spines are in shape of small processes in Tanytarsus lulu but not confirmed in other species of the ligulatus group. Another character that needs re-examination is the presence of sensilla chaetica on the mid leg basitarsus which form a distinct row (comb) in T. lulu , but have not been mentioned in descriptions of T. ligulatus , T. paraligulatus nor T. cf. ligulatus (Sanseverino 2006) . All species of the ligulatus group are close morphologically, thus their delimitation has to be based on detailed descriptions (given in the extended form for T. lulu ).

Figures

FIGURE 5. Tanytarsus lulu sp. nov., male. A, B: hypopygium in dorsal (A) and ventral aspect (B); C: anal point; D: superior volsella and digitus; E: median volsella; (C–E magnified ca. 3–4 times relative to A and B).