Pseudosmittia saetheri, Mauad, Melina, Siri, Augusto & Donato, Mariano, 2013

Mauad, Melina, Siri, Augusto & Donato, Mariano, 2013, New species of Pseudosmittia Edwards, 1932 and new records of Allocladius Kieffer, 1913 (Diptera: Chironomidae, Orthocladiinae) from South America, Zootaxa 3694 (5), pp. 445-460 : 447-449

Pseudosmittia saetheri sp. n.

( Figs 1–4 )

Material examined. ARGENTINA: Holotype male, Buenos Aires, Sierra de La Ventana, Aº Naposta, 38º 08' 42.0'' S, 62º 05' 35.6'' W, 300 m a.s.l., 11.i.2010, sweep net, M. Donato.

Etymology. Named in memory of Professor Ole Anton Saether, leader in chironomid systematics, who passed away during the elaboration of this paper.

Diagnosis. Distinguished from all other species of the genus by the combination of the following characters: R4+5 ending proximal to M3+4; virga triangular, consisting of a single spine without lateral spinules or additional structures; anal point covered by microtrichia; superior volsella and median volsella separated and about equally long, superior volsella digitiform with a strong anterobasal projection with apical seta; inferior volsella single, more or less triangular; Cu1 straight.

Male (n = 1). Total length 1.6 mm. Wing length 0.9 mm. Total length/wing length 1.78. Wing length/length of profemur 2.65. Coloration (specimen preserved in alcohol) uniformly dark brown with legs light brown.

Head. Antennae with 13 flagellomeres, without apical seta; AR 0.97, ultimate flagellomere 280 long. Temporal setae 6, divided in 4 inner verticals, outer verticals lacking, and 2 postorbitals. Clypeus with 5 setae. Tentorium 98 long and 20 wide. Palpomere lengths (1–5): 22; 27; 54; 66; 88.

Thorax ( Fig. 1 ). Antepronotum with 1 lateral setae. Dorsocentrals 8; prealars 3; supraalar absent. Scutellum with 4 setae.

Wing ( Fig. 2 ). R4+5 ending proximal to M3+4. VR 1.4. C extension 16 long. Brachiolum with 1 seta; other veins bare.

Legs. Spur of front tibia 37 long; spurs of mid tibia broken; of hind tibia: 17 and 39 long. Width at apex of front tibia 22; of mid tibia 22; of hind tibia 32. Comb with 11 setae. Lengths and proportions of legs in Table 1.

TABLE 1. Lengths (in µm) and proportions of legs of Pseudosmittia saetheri sp. n. (male, n = 1). Abbreviations: Femur (fe); Tibia (ti); Tarsomeres 1-5 (Ta1-5); Leg Ratio (LR), ratio of metatarsus to tibia; «Beinverhältnisse» (BV), combined length of femur, tibia, and basitarsus divided by combined length of tarsomeres 2-5; «Schenkel-Scheine-verhältnis» (SV), ratio of femur plus tibia to metatarsus.

Hypopygium ( Figs 3–4 ). Tergum IX with 2 setae, laterosternite IX with 4 setae. Anal point 20 long. Phallapodeme 35 long; transverse sternapodeme 75 long. Virga 20 long. Gonocoxite 132 long; length from base of gonocoxite to apex of inferior volsella/length of gonocoxite 0.16. Gonostylus 54 long; megaseta 10 long. HR 2.44; HV 2.96.

Remarks. The species P. saetheri keys with P. magdae in Andersen et al. 2010. The characters gonostylus simple against bilobed gonostylus with lateral lobe adpressed to gonostylus and superior volsella without tubercles against superior volsella with 2–4 large tubercles clearly separates the two species. In the male identification key of Ferrington & Saether (2011) P. saetheri keys in the dilemma 75 but the shape of the inferior volsella is different to those proposed by the authors. The species may be a variety of P. forcipata . The main differences consist in the longer median volsella, the anterobasal projection of the superior volsella with one strong seta, and the straight Cu1.

Habitat. This species was collected in the Napost stream, one of the most important permanent streams of the Ventania Hill system and drains in the Atlantic Ocean. This stream is originated by several headwaters of short length and small drainage in Naposta Hill at 750 m a.s.l. The flow is variable from low in the dry season (summer and winter) to high in the rainy season (autumn and spring). Naposta stream is characterized by clear water, rocky streambed, low conductivity and nutrient concentrations, neutral to slightly alkaline water and high dissolvedoxygen.

Figures

FIGURES 1 – 4. Pseudosmittia saetheri sp. n., male. 1, Thorax; 2, Wing; 3, Hypopygium with tergite IX removed, dorsal aspect to the right, ventral aspect to the left; 4, Hypopygium, dorsal aspect.