Procladius (Psilotanypus) travassosi ( Oliveira, Messias & Silva-Vasconcelos, 1992 ) Dantas & Hamada, 2018

Dantas, Galileu P. S. & Hamada, Neusa, 2018, Immature stages of Laurotanyus travassosi Oliveira, Messias & Silva-Vasconcelos, 1992 reveal a new synonymy in Tanypodinae (Diptera: Chironomidae), Zootaxa 4444 (4), pp. 462-470 : 463-469

Procladius (Psilotanypus) travassosi ( Oliveira, Messias & Silva-Vasconcelos, 1992) comb. nov.

Laurotanypus travassosi Oliveira et al. 1992: 410 ; Spies & Reiss (1996); Ashe & O'Connor (2009); Spies et al. (2009); Silva & Ekrem (2016).

Material examined. BRAZIL: Roraima state, Amajari municipality, Serra do Tepequem , 03°47'16.9''N, 61° 45'38.4''W, 09.vii.2016, G.P.S. Dantas: 1 male with larval and pupal exuviae (slide mounted) ; 1 male (slide mounted), light-trap ( INPA). Pará state, Oriximiná municipality, 20.ix.1980, S. Oliveira: 2 males (slide mounted), light-trap ( CEIOC-RJ).

Diagnose: Male —wings with two dark transverse bands; dorsomedian extension strongly reduced; scutal tubercle present. Pupa —cephalothorax and abdomen hyaline; thoracic horn somewhat cylindrical; plastron plate somewhat rounded; scar on TI present; lateral fringe on segments III–VI absent; anal lobe elongate, outer border convex, with 19 strong spines distal from the anal macrosetae; male genital sac wedge-shaped, apically tapered. Larva —S8 very close to DP; mola distally expanded to broad with bilobed apex; two small pointed accessory teeth on mola, adjacent to origin of seta subdentalis; pecten hypopharyngis with 5–6 teeth; paraligula with small points similar in siZe both in the external and internal margin.

Male (n= 1–3). Total length 2.33 mm. Wing length 1.10 mm. Total length/ wing length 2.12. Wing length/ length of profemur 5.19.

Coloration. Head and palps pale brown. Thorax dark-brown, with anterior anepisternum II pale ( Fig. 1B ). All legs brown. Wing with brownish veins and two dark transverse bands ( Fig. 1C ). Abdomen uniformly brown.

Head ( Fig. 1A ). AR 1.43. Antenna with 13 flagellomeres; flagellum 776 µm long, apical flagellomere 117 µm long, 30 µm wide at base. Temporal setae 12, uniserial to irregularly posteriorly. Clypeus square-shaped, 70 µm long, 98 µm wide, with 11–12 setae. Cybarial pump 169 µm long, orifice 47 µm from the base. Tentorium 130 µm long, 27 µm wide. Stipes 150 µm long. Palpomere lengths (1–3 and 5, in µm): 38, 47, 80, 152; fourth palpomere damaged. Eyes bare, separated by 275 µm, dorsomedial extension reduced.

Thorax ( Fig. 1B ). Antepronotum with 7 lateral setae, tubercle present. Acrostichals 30; dorsocentrals 10–13, uniserial; prealars 7–8; supraalar 1. Scutellum with 11–17 setae. Anepisternals, preepisternals and postnotals absent. Scutal tubercle present, with 3–4 strong setae.

Wing ( Fig. 1C ). 427 µm wide. VR 0.86; WW (width/length) 0.39. Costa produced, 1.06 mm long, costal extension 80 µm long. R2, R3 and R2+3 present; R2 reaching R2+3; R3 reaching C. MCu anterior to RM. Cu with petiole, 222 µm long. Brachiolum with 1 seta, R with 8 setae, R1 with 3–4, remaining veins bare. Squama with 18 setae. Anal lobe well developed.

Legs. Fore leg: tibia with an apical spur, 39 µm long, with an elongated apical tooth and 5 smaller inner teeth; tibia 41 µm wide at apex; internal margin with about 7 sensilla chaetica. Mid leg: tibia with two apical spurs, one 30 µm long, with an apical tooth and 4 inner teeth, another 33 µm long, with an apical tooth and 5 smaller inner teeth; tibia 40 µm wide at apex. Hind leg: tibia with two apical spurs, one 25 µm long, with an apical tooth and 4 inner teeth, another 36 µm long, with an apical tooth and 4 smaller inner teeth; tibia 46 µm wide at apex; pseudospurs in ta1, ta2 and ta3; tibial comb well defined, with 10 bristles. All legs with small claws, distally curved downwards and spatulate, without basal spines. Lengths and proportions of legs in Table 1.

Hypopygium ( Figs. 2A–D ). Tergite IX with 8 scattered setae. Anal point broad and blunted apically. Phallapodeme indistinct. Transverse sternapodeme distinctly arched. Superior volsella arched, 93 µm long, basal half slender and thicker, distal half expanded; a median heavily sclerotiZed keel is present ( Fig. 2B ). Gonocoxite robust, wider at the base, slightly narrowing towards the apex, 132 µm long, 82 µm wide. Gonostylus as in Figures 2C–D , 65 µm long, 30 µm maximum width; outer edge straight; a dorsomedial seta arising from a prominent tubercle; apical lobe slightly curved, 16 µm long, with a single seta rising from a distinct basal tubercle on external margin; megaseta lanceolate, 12 µm long, without dorsal lamella; inner lobe ( Fig. 2D ), with 4 bristles arising from prominent tubercles. HR 2.03. HV 3.58.

Pupa (n= 1). Coloration. Cephalothorax and abdomen hyaline.

Cephalotorax. Thoracic horn somewhat cylindrical ( Figs. 3A–B ), 214 µm long, maximum width 46 µm; external membrane hyaline, smooth, apparently without spines; respiratory atrium, filling almost entire thoracic horn lumen, wider medially, tapering toward the base ( Fig. 3C ), connected to the plastron plate by a wide neck; plastron plate somewhat rounded, 27 µm long, 25 µm wide ( Fig. 3A ). Basal lobe and thoracic comb absent. Thoracic membrane smooth.

Abdomen. Scar on TI present. Shagreen formed by groups of 2–5 small spines arranged in transverse lines; anal lobe with shagreen on basal half. Lateral fringe on segments III–VI absent. S VII with 4 LS setae ( Fig. 3C ), SVIII with 5 LS setae. Posterolateral corners of segment VIII project backwards. Anal lobe elongate ( Fig. 3D ), 280 µm long, 277 µm wide at base; outer border of anal lobe convex, with 19 strong spines distal from the anal macrosetae; inner border straight, apparently without spines. Male genital sac 161 µm long, 176 µm wide at base, wedge-shaped, apically tapered ( Fig. 3D ).

Larva (n = 1). Coloration. Head pale yellow; postoccipital margin dark-brown; apex of mandible dark; ligula brown, dark at apex. Procercus pale; anal setae and posterior parapod claws yellowish.

Head capsule ( Fig. 4A ). Oval; cephalic index 0.98. Chaetotaxy typical of Procladius , as in Figure 4A . Dorsally S5 quite anterior, DP, S8 and almost aligned, S8 very close to DP. Ventrally SSm medialmost, VP posterolateral, SSm, S10 and VP almost aligned.

Antenna. Length 140 µm long, A1 115 µm long, 26 µm maximum width, ring organ not observed, A2 16 µm long. AR 7.20.

Maxilla. Basal palp segment 35 µm long and 13 µm wide, with ring organ placed 17 µm from base. A1/P1 3.28, A2/P1 0.45.

Mandible ( Fig. 4B ). Apically curved. Length 100 µm, with 3 ventrolateral setae and 1 sensilla; mola distally expanded to a broad, protruding tooth with apically-directed, bilobed apex; without any inner tooth; two small pointed accessory teeth on mola, adjacent to origin of seta subdentalis. A1/MD 1.55–1.15.

Mentum and M appendage ( Fig. 4C ). With 8 dorsomental teeth on each side, labial vesicles well developed, egg shaped. M appendage triangular, bluntly rounded apically; pseudoradula 62 µm long, uniformly granulated.

Hypopharyngeal complex ( Fig. 4D ). Ligula with five teeth, anterior row of teeth concave; 59 µm long, 43, 35 and 34 µm wide at apex, middle and base respectively; point of inner teeth slightly inclined inwards. Paraligula 33 µm long, with small points similar in siZe, both in the external and internal margin. Pecten hypopharyngis with 5–6 teeth.

Body. With fringe of swim-setae. Anterior parapods separated medially, with simple claws. Posterior parapod without hooklets, all claws simple, smaller claws strongly curved ( Figs. 4E–G ). Subbasal seta of posterior parapod simple, 87 µm long. Procercus 118 µm long, 25 µm wide, with about 12 anal setae, 460 µm long. Supraanal seta 510 µm long. Anal tubules not measurable.

Systematic remarks. Up to now, the placement of Laurotanypus in Tanypodinae was uncertain and its validity questioned ( Spies, 2009; Silva & Ekrem, 2016). According to Oliveira et al. (1992) the genus is closely related to Procladius , being distinguished by the presence of a scutal tubercle, banded wings and gonostylus without heel. However, at least one species of Procladius has a scutal tubercle, and many species assigned to Procladius in the past are outdated and/or present incomplete descriptions. A gonostylus heel is present in species included in P. ( Holotanypus ) Roback, but there are species in Procladius without gonostylus heel. The banding pattern in the wing is also not considered a good feature to distinguish genera within Tanypodinae , being intrageneric variation present, as in Djalmabatista , considered the sister group of Procladius , transverse bands on the wings present in at least one species.

In the original description of Laurotanypus , the genitalia were not described in detail and some structures of the gonostylus and the superior volsella were ignored or not observed. In the specimens analyZed in this study, the superior volsella is well developed and divided in half by a well-sclerotiZed keel. The superior volsella is present in Procladius and varies in siZe and shape. In addition, both pupa and larva of L. travassosi are typical of Procladius . Features found in the pupa of P. travassosi comb. nov. as absence of a lateral fringe on the abdominal segments III–VI, anal lobe broad and paddle-like, with a fringe of spines on outer border, fit easily in the diagnosis of the genus. Likewise, larva of P. travassosi comb. nov. has a set of characters that fit to Procladius diagnose: a typical Procladius chaetotaxy of the head, mandibular mola distally expanded to a broad, protruding tooth, dorsomentum with 8 (in Procladius ranges from 6–8) light-brown tooth, ligula with 5 tooth and paraligula with small points similar in siZe. Thus, based mainly on the morphology of the immature stages, the genus Laurotanypus is now placed as a junior synonym of Procladius .

The male of P. travassosi comb. nov. does not fit easily in the diagnosis of any of the three subgenera of Procladius but it is more similar to P. ( Psilotanypus ) by the absence of heel and presence of an internal lobe on the gonostylus, even if in P. travassosi comb. nov. the superior volsella is elongated, while in P. ( Psilotanypus ) it is ovoid. Superior volsella elongated is found only in some species of P. ( Holotanypus ), but in this subgenus the gonostylus has a heel and the inner lobe is absent. In P. ( Procladius ) s. str. the superior volsella is ovoid and the inner lobe is absent; therefore, P. travassosi comb. nov. also does not fit in this subgenus. However, examining pupal and larval characteristics, P. travassosi comb. nov. fits easily in the diagnosis of P. ( Psilotanypus ), which corroborates Spies et al. (2009), who discussed the similarity of some species of Procladius (Psilotanypus) with P. travassosi comb. nov. at the adult stage. In accord with the diagnosis of P. ( Psilotanypus ), the pupa of this species has hyaline abdominal segments, thoracic horn cylindrical with plastron plate, scar on TI and absence of lateral fringe on SIII –VI, while the larva has paraligula with points similar in siZe, both on the internal and external margins.

Lastly, although the type material of P. travassosi comb. nov. is lost, there is still a possibility of tracing it. In addition, due to the fact that the material used for the redescription was not collected exactly in the type locality, a neotype was not designated in the present study.

Notes on biology. The larva of P. travassosi comb. nov. was collected associated with aquatic vegetation on the banks of a first order stream, 1.16 m in width and 0.42 m in depth. This watercourse is characteriZed by slightly acidic black water (pH = 6.18) with low electrical conductivity (1.88 mS/cm), high concentration of dissolved oxygen (10.72 mg /L) and temperature of 24.6°C. The opening of the canopy was small and the dominant substrate types in the stream beds were sand and both coarse and fine litter. According to Sioli (1991), this type of stream is poor in nutrients and its rich fauna is sustained by allochthonous inputs of organic material such as leaves, flowers, fruits and trees.

Distribution. According to Oliveira et al. (1992), the species has a wide distribution in the BraZilian territory, occurring from the extreme north to the southeast of the country, both in savanna and forest areas (AmaZon and Atlantic Forest).

Figures

FIGURE 1. Procladius travassosi (Oliveira, Messias & Silva-Vasconcelos, 1992) comb. nov., adult male. (A) Head. (B) Thorax. (C) Wing.

FIGURE 2. Procladius travassosi (Oliveira, Messias & Silva-Vasconcelos, 1992) comb. nov., adult male. (A) Dorsal view of hypopygium with right gonocoxite removed. (B) Dorsal view of hypopygium with left gonocoxite, TIX and anal point removed. (C) Gonostylus, dorsal view. (D) Gonostylus, ventral view.

FIGURE 3. Procladius travassosi (Oliveira, Messias & Silva-Vasconcelos, 1992) comb. nov., pupa. (A) Thoracic horn, with plastron plate in dorsal view. (B) Thoracic horn, with plastron plate in lateral view. (C) Basal half of thoracic horn. (D) LS setae of segment VII. (E) Anal lobe.

FIGURE 4. Procladius travassosi (Oliveira, Messias & Silva-Vasconcelos, 1992) comb. nov., larva. (A) Head capsule, ventral view to the left, dorsal view to the right. (B) Mandible. (C) M appendage, dorsomentum and labial vesicles. (D) Ligula and paraligula. (E-G) Small claws of posterior parapod.