A new species of Nigrobaetis Novikova & Kluge, 1987 (Ephemeroptera, Baetidae) from Tamil Nadu, India Author Sivaruban, T. PG & Research department of Zoology, The American College, Madurai- 625002, India. Author Srinivasan, Pandiarajan 0000-0001-8118-3256 PG & Research department of Zoology, The American College, Madurai- 625002, India. & srini 15.05.1996 @ gmail. com; https: // orcid. org / 0000 - 0001 - 8118 - 3256 srini15.05.1996@gmail.com Author Barathy, S. 0000-0002-9464-6464 Department of Zoology, Fatima College, Madurai- 625018, India. & barathyruban @ gmail. com; https: // orcid. org / 0000 - 0002 - 9464 - 6464 barathyruban@gmail.com Author Isack, Rajasekaran 0000-0002-9952-4335 PG & Research department of Zoology, The American College, Madurai- 625002, India. & iceisack 143 @ gmail. com; https: // orcid. org / 0000 - 0002 - 9952 - 4335 iceisack143@gmail.com text Zootaxa 2022 2022-01-12 5091 1 182 190 journal article 2619 10.11646/zootaxa.5091.1.8 c6ced354-271d-45dd-aad8-959fe9d0dd37 1175-5326 5840735 541C3DFD-939F-47B4-8571-97C297227DD5 Nigrobaetis klugei sp. nov. ( Figs 1–3 ) 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 . Paratypes (in alcohol): 1 male nymph ( Reg. No. ZSI –SRC/I/E/612), 2 male nymphs ( AMC ZN 203 ) and 9 female nymphs ( AMC ZN 204 ) same data as holotype . Mature nymph (in alcohol): Length : Body 3.2–3.5 mm ; cerci 1.1–1.3 mm ( Fig. 1A ); 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 ). 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 ). 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 ). Labrum: dorsal surface ( Fig. 2A ) 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 ). Incisors of left mandible ( Fig. 2C ) 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 ) 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 ) 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 ): Glossae slightly shorter than paraglossae; inner margin of glossae with a row of 10–11 setae; paraglossae as wide as glossae ( Fig. 2G ), 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 ). Femora. Villopore absent, outer margin of femora with about 11 stout, apically rounded setae with minute hairs ( Fig. 3B ); 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 ). Tarsi. Outer margin with ca. 8 small stout setae; inner margin with 8-9 spines. Tarsal claws ( Fig. 3F ) hooked with one row of about 11 acute teeth increasing in size towards apex. Midleg ( Fig. 3D ). 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 ). 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 ). FIGURE 1. Nigrobaetis klugei sp. nov. A) Mature nymph; B) Tergal coloration of immature nymph; C) Immature nymph; D) Antennae close to each other FIGURE 2. Nigrobaetis klugei sp. nov. A) Labrum; B) Hypopharynx; C) Left mandible (arrow indicates minute spines between prostheca and mola); D) Right mandible; E) Maxilla; F) Labium; G) Glossa and Paraglossa FIGURE 3. Nigrobaetis klugei sp. nov. A) Foreleg; B) Dorsal view of forefemur; C) Ventral view of forefemur; D) Midleg; E) Hindleg; F) Foreclaw; G) Postero-tergal spines of segment VII; H) Abdomen; I) Gill IV; J) Whorls of spines in cerci; K) Paraproct. Abbreviations: G–Gill, HWp–Hindwing pad, PTs- Postero-tergal spines FIGURE 4. Nigrobaetis paramakalyani (photos by K.A. Subramanian). A) Male nymph; B) Tergal coloration; C) Posterotergal spines of segment IV; D) Paraproct; E) Gill IV Abdomen : Tergites with numerous scale bases, posterior margin with long and pointed triangular spines in segments I to X ( Figs 3G–H ). Gills on segments I to VII ; gill I elongated and reduced ( Fig. 3H ); gills II to VII elliptic with dark margin, relatively long setae and serrated all along margins, tracheation well visible but poorly divided ( Fig. 3I ). Whorls of spines on cerci large and triangular in shape reaching 1/2 of the corresponding segment ( Fig. 3J ). Paraproct ( Fig. 3K ) 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 ); (ii) paraproct distally not expanded, with a reduced number of spines on distal margin ( Fig. 3K ); (iii) paraglossae slender, approx. as wide as glossae ( Fig. 2G ); (iv) absence of mediolateral spots on abdominal tergites ( Fig. 1B ); (v) outer margin of forefemora with 11 stout setae ( Figs 3A–C ); (vi) posterior margin of tergum with long and pointed triangular spines in segments I to X ( Figs 3G–H ). 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 ) 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.