Teloganopsis gracilis (Tshernova, 1952)

Gorovaya, E. A., 2021, Studies on mayfly Teloganopsis gracilis (Tshernova, 1952) (Ephemeroptera: Ephemerellidae), Far Eastern Entomologist 433, pp. 18-24 : 19-23

Teloganopsis gracilis (Tshernova, 1952)

Figs 1–26

Ephemerella gracilis Tshernova, 1952: 275 , figs. 79–82 (lectotype – mature larva, Russia:

Khabarovsky krai; deposited in Zoological Institute, Russian Academy of Sciences, St. Petersburg; designated by Kluge, 1995).

Ephemerella (Amurella) gracilis: Kluge, 1997: 212 .

Teloganopsis gracilis: Jacobus & McCafferty, 2008: 240 , fig. 49; Ubero-Pascal & Sartori,

2009: 103.

MATERIAL. Russia: Jewish Autonomous oblast, Amur River, Nizhneleninskoye Village ,

downstream from the bridge, 09.VII 2018, 1 middle-aged larva (О. Kudrevskii).

DESCRIPTION. Length (mm): body 5.0; cerci 4.2. Body slender, mostly beige with dark brown spots and wide beige stripe along medial line ( Figs 1–3 ). All sclerotized structures abundantly covered with micro-thin transparent hairs.

Head without tubercles or projections, beige with two longitudinal brown strips ( Fig. 4 ).

Upper part of eyes ginger, lower one black. Antennae long. Labrum light brown, densely covered with setae; length to width ratio 1:2 ( Fig. 5 ). Hypopharynx wide, rounded; superlinguae wide, oviform, with long thick setae along anterior and inner margins ( Fig. 6 ). Mandible

( Figs 7, 8 ) broad; left incisor ( Fig. 9 ) with 4, right ( Fig. 10 ), with 3 teeth. Maxilla wide, apex pointed with four teeth, densely covered by multitudinal long thin setae ( Fig. 11 ). Inner margin of maxilla with a pair of dentisetae, with 2 rows inconsiderable in number thick and strong setae. Maxillary palpus missing. Labium wide, oval, densely pubescent on anterior margin ( Fig. 12 ). Glossae rounded, wide, closely approximate. Labial palpus 3-segmented.

1st and 2nd segments of labial palpus wide, oval; 3rd segment conical; transition from 2nd to

3rd segment smooth.

Thorax ( Figs 13, 14 ) sculptured with lightened wide zone along medial line which surro-

unded with wide dark brown stripes with symmetrical large beige spots of various shape. Pronotum wide with two high rounded medial tubercles. Anterior margin of pronotum is raised, bent dorsally. Mesothorax is separated by transverse sloping roller and has 3 high rounded tubercles: 2 symmetrical medial, 1 posterior. Rudiments of fore wings light beige.

ventral view.

Legs beige ( Figs 15–17 ). Length (mm) of segments of legs (femur, tibia, tarsus): fore:

0.9; 0.8; 0.5; mid: 1.0; 0.9; 0.6; hind: 1.1; 1.5; 0.6. Fore and mid femora moderately dilated medially, hind one – narrower. All femora covered with rare long strong clavate setae. Dorsal surface of fore femur with some roundish setae near its articular with tibia. Dorsal surface of superlinguas; 7, 8 – mandibles, dorsal view (7 – left, 8 – right); 9, 10 – incisors, ventral view

(9 – left, 10 – right); 11 – maxilla; 12 – labium.

view, 14 – lateral view); 15–17 legs (15 – fore, 16 – mid, 17 – hind); 18,19 – claws (18 – fore leg, 19 – mid leg); 20, 21 – abdomen (20 – dorsal view, 21 – lateral view); 22 – unpaired tubercle of tergite with setae; 23 – setae of lateral angles and caudal margins of tergites; 24,

25 – tergaliae (24 – I pair, 25 – II pair); 26 – caudal filament.

mid and hind legs with medial zones of roundish different-sized setae along the whole surface of femurs. All tibiae and tarsi with 2 rows of numerous pointed setae on inner margin. All tibiae also have wide roundish setae that ranged chaotically over the whole surface. All claws with long thin apical tooth, one wide massive subapical tooth and row with

8 denticles ( Figs 18, 19 ).

Abdomen. Tergites with wide beige stripe along whole medial line and dark brown symmetrical pattern on sides of it. This pattern particularly bright and extensive on tergites VI–X

( Fig. 20 ). Caudal margins of tergites with unpaired tubercles along medial line. These tubercles particularly well-marked on tergites II–VII ( Fig. 21 ) and covered by roundish setae ( Fig. 22 ).

Lateral margins of tergites bent distally; caudal corners arrow-headed, with elongated oval setae ( Fig. 23 ). Sternites beige with rows of paired wide dark brown spots ( Fig. 3 ). Tergaliae

( Figs 24, 25 ) asymmetrical with roundish elongated inner-apical angle, trefoil-shaped spot and ventral lamella divided into lobes. Length (mm) of tergaliae I–V: 0.8; 0.8; 0.75; 0.6;

0.25. Caudal filaments in base and in apical 2/5 beige, in middle part (2/5 from base) brown

( Fig. 26 ).

DIAGNOSIS. The claws of the larva T. gracilis have enlarged preapical denticle, this indicates to its affiliation with the genus Teloganopsis . The main difference of this species from other members of the genus including T. lenoki (Tshernova, 1952) , T. punctisetae

(Matsumura, 1931) and T. orbicularis Gorovaya, 2019 from the Russian Far East is unpaired tubercles, situated on the posterior margin of tergites. The similar but very small, hardly visible triangular projections in the middle of posterior margin of tergites II–V are present only in T. media .

Michel Sartori (2014) believes that T. media is unique among the genus Teloganopsis in the presence of tubercles on the thorax. However, the researched larva also has tubercles on the thorax. This is a new key feature that was not specified in the previous description of T.

gracilis. A large sagittal light brown band on the thorax in T. media and lightened wide zone along the medial line in T. gracilis are noted as other external characteristics. There are differences in the structure of the mouth parts of these two species, but they are not so pro-

nounced as the shape of the claws, shape and size of the denticles on the claws. The caudal angles of tergites in T. media are weakly expressed, while in T. gracilis they are strongly pointed.

DISTRIBUTION. Russia: Khabarovsky krai, Jewish Autonomous oblast (Amur River,

middle and low reaches).

Figures

Figs 1–3. Larva of Teloganopsis gracilis, habitus. 1 – dorsal view; 2 – lateral view; 3 –

Figs 4–12. Larva of Teloganopsis gracilis. 4 – head; 5 – labrum; 6 – hypopharynx and

Figs 13–26. Larva of Teloganopsis gracilis. 13, 14 – pro- and mesonotum (13 – dorsal