Saetheria tylus ( Townes, 1945 )

Orel, Oksana V., 2014, To systematics of the genus Saetheria Jackson (Diptera, Chironomidae) from the Russian Far East, Zootaxa 3802 (1), pp. 65-74 : 71-73

Saetheria tylus ( Townes, 1945)

( Figs 16–17 )

Harnischia (Cladopelma) tylus Townes, 1945: 150 , fig. 170; Townes 1952: 92.

Chironomus (Cryptochironomus) tylus (Townes) , Sublette & Sublette 1965: 168.

Paracladopelma cfr. nereis Mozley, Garcia, 1972: 109.

Paracladopelma nagaraelongata Sasa, 1989: 65 , Plate 19 fig. 41; Sasa & Okazawa 1992: 43; Sasa & Kikuchi, 1995: 102, fig. 21B; Sasa, 1998: 31.

Parachironomus taishoabeus Sasa & Tanaka, 2001: 46 , Plate 1 fig. 3.

Saetheria tylus (Townes) , Jackson 1977: 1352, figs 29, 30, 31; Saether 1983: 400, figs 2–4; Pinder & Reiss 1986: 435, fig. 10.70 (A–D); Oliver et al. 1990: 52; Kobayashi 2007: 10 , figs 6–7; Yan et al. 2011: 41 .

Material examined. PRIMORYE TERRITORY: male, Ussuryiskiy Region, Razdol’naya River basin, Kraunovka River, 21.07.2004, Arephina T.I.

Diagnostic characters. The male of S. tylus (Townes) is distinguished by the following combination of features: wing length 1.7 mm; AR 1.74; small frontal tubercles present; anal point spoon-shaped; superior volsella consist of bare dorsal lobe with a finger-shaped sclerotized projection and elongated foot-shaped ventral lobe covered with microtrichia and bearing 1 strong apical seta and 1 weaker seta in the apical third; gonostylus narrowed in the proximal third.

Male (n=1). Total length 3.0 mm. Wing length 1.7 mm. Total length / wing length 1.76.

Colouration. Pedicel of antenna, mesonotal stripes and postnotum yellowish brown, ground colour and scutellum pale yellowish. Abdomen yellowish. Fore legs yellowish with brown distal end of femora, proximal third and distal end of tibia, ta1–5 gradually darkened toward ends, tibiae sometimes brown. Mid and hind legs yellowish, ta1–5 gradually darkened toward ends.

Head. Frontal tubercles small (5.1 µm long, 3.4 µm wide). Antenna 856 µm long; ultimate flagellomere 544 µm long; AR 1.74. Verticals 12–14. Clypeus with 10 setae. Maxillary palp 462 µm long; length of palpomeres 2–5 (in µm): 37, 109, 122, 194. Antenna length / palp length 1.85.

Thorax chaetotaxy. Antepronotals 2, acrostichals 4, dorsocentrals 8–9, supraalar 1, prealars 3. Scutellum with 6 setae.

Wing 0.48 mm wide. Veins R with 6–7 setae, R4+5 with 2 setae. Squama with 4 setae; brachiolum with 1 setae. VR 1.31.

Legs. Spurs of middle tibia 24 µm, of hind tibia 24 and 31 µm long. Lengths and proportions of legs as in Table 3 .

Hypopygium ( Figs 16–17 ). Laterosternite IX with 3 strong setae. Anal point drop-shaped (length 51 µm, width 17 µm) at the base with 3 strong medial and 5–6 weak lateral setae. Gonocoxite 102 µm long, with 3 setae on inner margin. Transverse sternapodeme 51 µm wide. Phallapodeme 75 µm long. Superior volsella elongated foot-shaped (58 µm long and 31 µm wide in the base) composed of dorsal and ventral lobes. Dorsal lobe bare with a fingershaped sclerotized projection (17 µm long), ventral lobe covered with microtrichia and bearing 1 strong apical seta (27 µm long) and 1 weaker seta (10–14 µm long) in the apical third. Inferior volsella with rounded apical part and covered with microtrichia. Gonostylus (136 µm long, 20–24 µm wide) narrowed in the proximal third and apically round. HR 0.75.

Pupa is described by Jackson (1977) and redescribed by Saether (1983) and Pinder & Reiss (1986).

Larva is described by Jackson (1977).

Remarks. The adult male of S. tylus (Townes) from Primorye Territory is almost indistinguishable from the description of specimens of this species by other authors ( Table 4 ). The species affiliation larvae of S. tylus described by Kobayashi (2007), is questionable, as the larvae have 5-segmented antenna and it are not associated with the male. The larva of Chironominae genuinae № 9 described by Lipina (1926) from Oka River is somewhat different from larva of S. tylus by presence of a large tooth in middle of premandible and seta subdentalis a narrow blade-like. The larva of S. tylus has 3 large apical teeth and 1 small proximal tooth on premandible and seta subdentalis a wide blade-like ( Jackson 1977).

Distribution. Saetheria tylus (Townes) is distributed in the Holarctic Region ( Saether & Spies 2004). This species is known from Japan ( Kobayashi 2007). In Russian Far East it is recorded from Primorye Territory only.

Figures

FIGURES 14 – 17. Adult males of Saetheria tamanipparai (Sasa) (14 – 15) and Saetheria tylus (Townes) (16 – 17). 14, 16 — hypopygium, dorsal view; 15, 17 — superior volsella, ventral view. Scale bar 50 µm.

Tables

TABLE 3. Lengths (in µm) and proportions of legs of Saetheria tylus (Townes), male (n = 1).

	fe	ti	ta1	ta2	ta3	ta4	ta5
p1	630	399	735	389	273	189	105
p2	588	504	252	147	105	84	63
p3	651	651	420	231	210	105	84

TABLE 4. Morphological characteristics of adult males of S. tylus (Townes) by various authors.

Morphological characters	Literature data Townes 1945	Jackson 1977	Sasa 1989	Sasa & Tanaka 2001	Kobayashi 2007	Out data
TL	–	3.0–3.2	2.72	3.02–3.18	2.3–2.8	3.0
WL	1.5	1.4–1.5	1.29	1.30–1.52	1.34–1.60	1.7
AR	2.1	1.5–1.7	–	1.82–2.13	1.71–2.00	1.74
LR	1.85	1.7–1.9	2.0	–	2.10–2.19	1.84
Antepronotals	–	2	2	2	2–3	2
Acrostichals	–	4–6	8	8–10	7–11	4
Dorsocentrals	–	8–9	7	7–8	8–9	8–9
Prealars	–	3	3	3–4	2–3	3
Scutellars	–	5–8	6	10–12	5–10	6
Squama	“without a fringe of hairs”	3	2–3	2–3	2–3	4