A new species of Nigrobaetis Novikova & Kluge, 1987 (Ephemeroptera, Baetidae) from Tamil Nadu, India Sivaruban, T. Srinivasan, Pandiarajan Barathy, S. Isack, Rajasekaran Zootaxa 2022 2022-01-12 5091 1 182 190 Sivaruban & Srinivasan & Barathy & Isack, 2022 Sivaruban & Srinivasan & Barathy & Isack 2022 [151,374,798,825] Insecta Baetidae Nigrobaetis Animalia Ephemeroptera 1 183 Arthropoda species klugei sp. nov.  ( Figs 1–3)   Materials Examined.   Holotype(in alcohol): Femalemature 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 ma.s.l;  24/I/2021, Pandiarajan Srinivasan& Rajasekaran Isack.   Paratypes(in alcohol): 1 malenymph ( Reg. No. ZSI–SRC/I/E/612), 2 malenymphs ( AMC ZN 203) and 9 femalenymphs ( 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 Vlight brown; sternites VIand VIIdark 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 VIIelliptic 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  Nigrobaetisby 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 mwide, 2.1–2.4 cmdepth). The water temperature ranges between 26°C–28°C; pH 7.1–7.4. Substratum is mainly made of rock, cobbles and gravel. 3436308303 2021-01-24 ZSI Pandiarajan Srinivasan & Rajasekaran Isack India Female 195 9.697223 Rajapalayam district 21 77.67083 South 1 183 1 Tamil Nadu holotype 3436308304 ZSI, AMC Reg. No. India 1 183 ZN 203 3 3 Tamil Nadu paratype 3436308301 [430,1110,1015,1041] 2021-01-24 AMC Pandiarajan Srinivasan & Rajasekaran Isack India Female 195 9.697223 Rajapalayam district 21 77.67083 South 1 183 ZN 204 9 9 Tamil Nadu paratype