Choroterpes (Euthraulus) kanagae Muthukatturaja and Balasubramanian, 2025

Choroterpes (Euthraulus) kanagae Muthukatturaja and Balasubramanian sp. nov.

( Figs 1–54 View FIGURES 1–2 View FIGURES 3–8 View FIGURES 9–13 View FIGURES 14–26 View FIGURES 27–42 View FIGURES 43–47 View FIGURES 48–54 )

Type material: Holotype: male imago (ZSI/SRC Reg. No. I/E/819), INDIA, River Cauvery , Srirangapatna, Mandya District, Karnataka state, 20–I–2023, 674 m a.s.l, (12°25'38” N, 76°40'43” E), colls. Muthukatturaja & Balasubramanian GoogleMaps . Paratypes: 4 male imagoes (ZSI/SRC Reg. No. I/E/820), 5 mature larvae (ZSI/SRC Reg. No. I/E/821) GoogleMaps , 5 male imagoes (SVNCZM Reg. No. 01) and 10 mature larvae (SVNCZM Reg. No. 02) same data as holotype GoogleMaps .

Diagnosis: The new species is differentiated from all other known species of the subgenus Choroterpes (Euthraulus) by the following combination of characters: median emargination of labrum moderately cleft with 5 blunt denticles ( Figs 3–4 View FIGURES 3–8 ); femora with dark brown maculae on medial and distal area ( Figs 14–16 View FIGURES 14–26 ); claw slender, curved with 17 denticles ( Figs 24–26 View FIGURES 14–26 ); abdominal terga brown with a pale median line progressively wider on terga V–IX ( Fig. 1 View FIGURES 1–2 ); tergalius I absent ( Fig. 1 View FIGURES 1–2 ); dorsal lamella of tergalius VII terminated with two processes ( Fig. 42 View FIGURES 27–42 ); forewing milky transparent with 10–12 cross veins at stigmatic area ( Fig. 48 View FIGURES 48–54 ); costal projection of hind wing acute ( Fig. 50 View FIGURES 48–54 ); segment I of gonostylus slender without inner-apical angle ( Fig. 51 View FIGURES 48–54 ); penis slender, elongated, little longer than ½ of gonostylus length ( Fig. 52 View FIGURES 48–54 ).

Larva ( Figs 1–2 View FIGURES 1–2 ): Body length (excluding cerci) 5.5–6.5 mm; cerci length 5.0– 5.5 mm; paracercus length 5.5–6.0 mm; head width 1.0 mm; head length 0.8 mm; antenna length 1.9 mm; labrum width 0.4 mm; labrum length 0.2 mm; compound eye length 0.3 mm; compound eye width 0.4 mm; distance between compound eyes 0.2 mm; length of fore femur/ tibia/ tarsus 1.4/ 1.4/ 0.6 mm; length of middle femur/ tibia/ tarsus 1.3/ 1.3/ 0.4 mm; length of hind femur/ tibia/ tarsus 1.6/ 1.6/ 0.3 mm. General body colouration dark to pale brown. Head: colouration dark brown to yellowish brown; frontal and epicranial suture paler; vertex brown; antennae scape and pedicel pale yellow to translucent, flagellum translucent; compound eyes black in female; upper portion of eye brown and lower black in male. Mouthparts: median emargination of labrum moderately cleft with 5 blunt denticles ( Figs 3–4 View FIGURES 3–8 ), proximal and distal transverse row of setae arched; proximal transverse row of setae feathered, about 1.5× shorter than distal transverse row, lateral margin with a row of spike-like setae; medial dorsum with sparse spike-like setae; mandibles ( Figs 5–8 View FIGURES 3–8 ) with outer margin moderately convex with a group of thin long setae; left mandible with two thin long setae below the mola, inner and outer incisors with three denticles, outer margin of inner incisor with two prominent serrations, prostheca with well-developed processes and a incisor like apparatus; right mandible with 10–12 thin long setae below the mola, outer incisor with three denticles and few serrations at inner margin, inner incisor with two denticles and few serrations at outer margin, prostheca well-developed and bifurcated; subapical ventral row of maxilla with about 11 comb-like setae present at nearly apex of medio-apical projection, maxillary palp three segmented, segment I & II more or less equal in length, segment III small and apically with micro denticles, inner margin of maxillary palp with 6–8 setae on segment II and 4 setae on segment III, outer distal margin of segment III with tuft of thin setae ( Figs 9–10 View FIGURES 9–13 ); lingua of hypopharynx deeply cleft, superlingua rounded at apex and numerous thin setae at anterior margin ( Fig. 11 View FIGURES 9–13 ); surface of glossae of labium ( Fig. 12 View FIGURES 9–13 ) with numerous stout feathered setae, inner apical margin with a few stout setae, anterior margin of paraglossae with rows of stout setae and numerous thin long setae, labial palp three segmented, segment I and II more or less subequal in length, segment III short apically with micro denticles, outer margin of segment I with row of long spike-like setae, inner margin with few short and medium-sized spike-like setae, outer margin of segment II with few thin long setae, outer margin of segment III with tuft of thin setae, mesal margin with 4 stout setae progressively longer posteriorly, a row of short spike-like setae on submarginal areas. Thorax: terga dark brown to yellowish brown; pronotum wider than head; anterior margin with few spike-like setae; sterna white; femora of legs with dark brown maculae on medial and distal area; tibia and tarsi yellowish brown. Foreleg ( Figs 14, 17, 21 & 24 View FIGURES 14–26 ): coxae brown with a few spike-like setae on surface; trochanter with an arch of stout setae; proximal half of femur slightly broad; proximal outer and inner margins with a row of bipectinate setae; outer margin with two rows of few long and short spatulate setae and a row of thin long setae; inner margin with a row of spatulate setae and thin long setae; inner margin with rows of pectinate setae; surface and outer margin with sparse thin long setae; inner margin of tarsi with a row of stout setae; claw slender, curved with 17 denticles. Midleg ( Figs 15, 18, 22 & 25 View FIGURES 14–26 ): coxae similar to foreleg without setae; trochanter with a row of spatulate setae on surface and a bipectinate setae basally; proximal outer margin of femur with a row of spike-like setae; outer margin with two rows of spatulate setae and a row of thin long setae; inner margin with two rows of spatulate setae and a row of stout setae; mesal margin with rows of sparse spatulate setae (setae absent on disto-mesal margin); inner margin of tibia with a row of spatulate setae and stout setae; outer margin and surface area with sparse thin long setae; inner margin of tarsi with a row of very short stout setae; claw similar to foreleg. Hindleg ( Figs 16, 19, 20, 23 & 26 View FIGURES 14–26 ): coxae similar to midleg; trochanter similar to midleg with a spatulate setae basally; femur similar to midleg; inner and outer margins of tibia with a row of long and short spatulate setae; basal 2/3 of lateral margin with irregular rows of bipectinate setae; inner margin of tarsi with a row of very short stout setae; claw similar to foreleg. Abdomen: Terga brown with a pale median line progressively wider on terga V–IX; posterior margin of terga I–VII with a dark brown band; apical margin of tergum X pale; sterna pale; sternum VIII with a pale brown marking; posterior half of sterna X pale brown; posterior margins of abdominal terga I–II with minute denticles ( Figs 27–28 View FIGURES 27–42 ), of terga III–X with long, pointed denticles increasing toward tergum X ( Figs 29–36 View FIGURES 27–42 ); sterna without denticles; posterolateral spines of terga VIII–IX long and incised ( Fig. 13 View FIGURES 9–13 ). Tergalii ( Figs 37–42 View FIGURES 27–42 ): tergalius I absent; tergalii II–VII bilamellate, ventral lamella broader than dorsal lamella; all lamellae of tergalii II–VI terminated with three processes; dorsal lamella of tergalius VII terminated with two processes (ventral lamella with three processes); dorsal lamella slightly darker than ventral lamella; tracheae black; paracercus slightly longer than cerci; annulations and articulations of cerci and paracercus with a whorl of stout setae.

Male imago ( Figs. 43–46 View FIGURES 43–47 ): Body length (excluding cerci) 6.5–7.5 mm; cerci length 7.0–8.0 mm; paracercus length 8.0–9.0; head width 1.0 mm; head length 0.5 mm; antenna 1ength 0.9 mm; compound eye length 0.5 mm; compound eye width 0.5 mm; distance between compound eye 0.0 mm; length of fore femur/ tibia/ tarsi 1.0/ 1.7/ 1.7 mm; length of middle femur/ tibia/ tarsi 1.1/ 0.9/ 0.4 mm; length of hind femur/ tibia/ tarsi 1.2/ 0.9/ 0.5 mm; forewing length 6.3 mm; forewing width 2.0 mm; hindwing length 1.0 mm; hindwing width 0.5 mm; forceps length 0.5 mm; penis length 0.32 mm. Body colouration as in figures 43–46. Head: dark brown; compound eyes turbinate; dorsal portion of eyes reddish brown; ventral portion blackish; scape and pedicel of antennae yellowish brown to pale yellow; flagellum pale yellow to translucent. Thorax: terga dark brown to yellowish brown; lateral margins pale with brown markings; base of wings paler; sterna dark brown to white. Legs: coxae darker; trochanter pale brown; fore femur tan brown; distal region blackish; proximal half of tibia dark brown remainders translucent; tarsi and claw translucent; tarsal segments without spines; pair of claw paddle-like; middle and hind femur tan brown colouration observed only on the middle region; distal region blackish; tibia, tarsi and claw colouration similar to foreleg; middle and hind tarsal segments I–IV with a stout spine on apico-ventral region ( Fig. 47 View FIGURES 43–47 ); dissimilar claws (one paddle-like other apically hooked). Wings: forewings ( Fig. 48 View FIGURES 48–54 ) milky transparent, membrane hyaline and veins darker with a small bulla; stigmatic area with 10–12 cross veins; costal projection of hind wings acute ( Figs 49–50 View FIGURES 48–54 ). Abdomen: terga blackish brown to tan brown; lateral margin tan brown; terga I translucent, posterior margin with a black marking medially; anterior ½ of tergum II translucent, posterior ½ with blackish brown marking; terga III–VIII with a distinct W-shaped blackish brown marking, remaining area yellow; blackish brown marking on tergum IX fused; sterna brown to translucent; sternum I translucent; sterna II–IX with a lateral brownish marking; colouration of lateral brownish marking diluted to yellowish brown towards last abdominal segments; pleura brown. Genitalia ( Figs 51–54 View FIGURES 48–54 ): gonostylus brown basally, translucent apically, three segmented; segment I slender, apically narrow without inner-apical angle; middle of inner margin of segment I with a few spines; segment II ca. 0.1×length of segment I, segment III ca. 0.08 ×length of segment I; penis slender, little longer than ½ of gonostylus; posterior margin of penal plate broadly round with sparse minute barbs on the surface; cerci pale yellow to translucent.

Etymology: The species name Choroterpes (E.) kanagae is dedicated to Mrs. Kanaga Balasubramanian, whose dedication is inevitable and immeasurable in all our aquatic insect collections in the Western Ghats, India. Name in apposition.

Distribution: Karnataka, India ( Fig. 36 View FIGURES 27–42 ).