Nigrobaetis klugei, Sivaruban & Srinivasan & Barathy & Isack, 2022

Sivaruban, T., Srinivasan, Pandiarajan, Barathy, S. & Isack, Rajasekaran, 2022, A new species of Nigrobaetis Novikova & Kluge, 1987 (Ephemeroptera, Baetidae) from Tamil Nadu, India, Zootaxa 5091 (1), pp. 182-190 : 183-188

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Nigrobaetis klugei

sp. nov.

Nigrobaetis klugei sp. nov.

( Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Materials Examined. Holotype (in alcohol): Female mature nymph (Reg. No. ZSI –SRC/I/E/611), South India, Tamil Nadu, Rajapalayam district , Sastha falls , 9°41’50’’N & 77°40’15’’E; 195 m a.s.l; 24/I/2021, Pandiarajan Srinivasan & Rajasekaran Isack GoogleMaps . Paratypes (in alcohol): 1 male nymph (Reg. No. ZSI –SRC/I/E/612), 2 male nymphs ( AMC ZN 203 View Materials ) and 9 female nymphs ( AMC ZN 204 View Materials ) same data as holotype GoogleMaps .

Mature nymph (in alcohol): Length: Body 3.2–3.5 mm; cerci 1.1–1.3 mm ( Fig. 1A View FIGURE 1 ); terminal filament shorter in female (0.7–0.8 mm) than in male (0.9–1.0 mm).

Coloration: Head uniformly brown without vermiform marks on vertex and frons. Eyes of male nymphs reddish brown, thorax dark brownish without any pattern. Legs generally whitish, dorsal side of femora with a brown band at 2/3 distally and dark brown apically ( Figs 3B & 3C View FIGURE 3 ). Abdominal tergite I light brownish, tergites II and III dark brownish, tergite IV light brownish, tergites V-VII dark brownish, tergite VIII light brownish; tergite IX whitish; tergite X dark brownish without any spots (coloration paler in younger specimens) ( Figs 1B& 1C View FIGURE 1 ). Entire surface of tergites covered with scales. Abdominal sternites I to V light brown; sternites VI and VII dark brownish; sternites VIII and IX paler. Cerci dark brownish in proximal part and paler in the distal part.

Head: Antennae close to each other ( Fig. 1D View FIGURE 1 ). Labrum: dorsal surface ( Fig. 2A View FIGURE 2 ) with 1+3 long simple stout setae on the distal half and 6-7 small simple setae scattered on the surface; ventral surface with three to four small pointed setae near lateral margin; distal margin with two kinds of setae: laterally 7 to 8 long, feathered setae and medially shorter, slightly feathered setae. Hypopharynx: lingua trilobed, covered with small simple setae; superlinguae with thin setae apically and laterally ( Fig. 2B View FIGURE 2 ). Incisors of left mandible ( Fig. 2C View FIGURE 2 ) with 6 denticles; prostheca with 7 broad denticles and a reduced comb-shaped structure; margin between prostheca and mola proximally with 2 large spines and distally with 5 minute spines; tuft of setae at apex of mola absent. Incisors of right mandible ( Fig. 2D View FIGURE 2 ) with 8 denticles; prostheca with 7 denticles; margin between prostheca and mola with 11-12 medium pointed spines; tuft of setae at apex of mola present. Maxillae ( Fig. 2E View FIGURE 2 ) with 3 broad canines; absence of setae at base of canines, 3 setae at base of lacinia; palp two-segmented; segment I approximately 1.1 x length of segment II; segment II apically rounded, covered with thin setae. Labium ( Fig. 2F View FIGURE 2 ): Glossae slightly shorter than paraglossae; inner margin of glossae with a row of 10–11 setae; paraglossae as wide as glossae ( Fig. 2G View FIGURE 2 ), falcate, with long and stout setae on outer margin and dorsally 4 long simple setae near inner margin; labial palp three-segmented, segment I subrectangular and subequal in lengths to segment II and III combined; simple small setae on the lateral margin of segment I; segment II with a dorsal oblique row of three long pointed setae; segment III truncated and apically rounded with medium to small pointed setae.

Thorax: Foreleg ( Fig. 3A View FIGURE 3 ). Femora. Villopore absent, outer margin of femora with about 11 stout, apically rounded setae with minute hairs ( Fig. 3B View FIGURE 3 ); inner margin with 13-14 small stout setae which are variable in size. Tibiae. Outer margin with 11 small simple setae; inner margin with 9-10 spines, with a single large comb-shaped, unipinnate seta and a bipinnate seta present on its apex ( Fig. 3A View FIGURE 3 ). Tarsi. Outer margin with ca. 8 small stout setae; inner margin with 8-9 spines. Tarsal claws ( Fig. 3F View FIGURE 3 ) hooked with one row of about 11 acute teeth increasing in size towards apex. Midleg ( Fig. 3D View FIGURE 3 ). Outer margin of femora with about 8 stout, apically rounded setae and with minute hairs; inner margin with 11-12 small stout setae. Tibiae. Outer margin with 11 small simple setae present; inner margin with 9 small spines present. Tarsi. Outer margin with 7-8 small simple setae; inner margin with 5 small spines. Claws of mid and hind legs similar to that of foreleg. Hindleg ( Fig. 3E View FIGURE 3 ). Outer margin of femora with 9 stout apically rounded setae. Tibiae. Outer margin bare; inner margin with 10 small spines. Outer margin of tarsi bare; inner margin with 5 small spines. Hindwing pads present ( Fig. 3G View FIGURE 3 ).

Abdomen: Tergites with numerous scale bases, posterior margin with long and pointed triangular spines in segments I to X ( Figs 3G–H View FIGURE 3 ). Gills on segments I to VII; gill I elongated and reduced ( Fig. 3H View FIGURE 3 ); gills II to VII elliptic with dark margin, relatively long setae and serrated all along margins, tracheation well visible but poorly divided ( Fig. 3I View FIGURE 3 ). Whorls of spines on cerci large and triangular in shape reaching 1/2 of the corresponding segment ( Fig. 3J View FIGURE 3 ). Paraproct ( Fig. 3K View FIGURE 3 ) with abundant scale bases, but almost no setae and reduced number of spines on distal margin (three large and two small spines); postero-lateral extension with scale bases, margin with numerous blunt, triangular, small spines.

Imago: Unknown

Diagnosis: Nigrobaetis klugei sp. nov. can be differentiated from other Oriental species of Nigrobaetis by the following combination of characters: (i) dorsal surface of the labrum with 1+3 long simple stout setae on the distal half ( Fig. 2A View FIGURE 2 ); (ii) paraproct distally not expanded, with a reduced number of spines on distal margin ( Fig. 3K View FIGURE 3 ); (iii) paraglossae slender, approx. as wide as glossae ( Fig. 2G View FIGURE 2 ); (iv) absence of mediolateral spots on abdominal tergites ( Fig. 1B View FIGURE 1 ); (v) outer margin of forefemora with 11 stout setae ( Figs 3A–C View FIGURE 3 ); (vi) posterior margin of tergum with long and pointed triangular spines in segments I to X ( Figs 3G–H View FIGURE 3 ).

Etymology: The new species is named after Dr. N. J. Kluge, for his outstanding contribution to mayfly systematics and phylogeny.

Ecology: The nymphs of N. klugei sp. nov. were collected in the Sastha falls ( Fig. 5 View FIGURE 5 ) of Western Ghats (5–7 m wide, 2.1–2.4 cm depth). The water temperature ranges between 26°C–28°C; pH 7.1–7.4. Substratum is mainly made of rock, cobbles and gravel.


Department of Biologics Research


Royal British Columbia Museum - Herbarium


Mykotektet, National Veterinary Institute