Indobaetis microfolius, Kluge, Nikita J. & Novikova, Eugenia A., 2014

Kluge, Nikita J. & Novikova, Eugenia A., 2014, Systematics of Indobaetis Müller-Liebenau & Morihara 1982, and related implications for some other Baetidae genera (Ephemeroptera), Zootaxa 3835 (2), pp. 209-236 : 223-226

Indobaetis microfolius sp.n.

( Figs 45–75 )

Material. Holotype: L-S♂ {specimen [IV] (5)}: INDIA, state Karnataka, Shivamogga district, a small mountain forest stream—tributary of river Agumbe-hole between village Malandur and the road Agumbe—Sringeri, about 4 km ESE of Agumbe, 16.I.2013, coll. N. Kluge, L. Sheyko. Paratypes: the same locality, 1 L/S♀, 1 larva. Descriptions.

Larva. CUTICULAR COLORATION: Dorsum of head, thorax and abdomen uniformly light brown. Thoracic and abdominal sterna colorless. Legs nearly uniformly light brown. Caudalii nearly uniformly light brow.

HYPODERMAL COLORATION: Abdominal terga can be brown, as in subimago.

SHAPE AND SETATION: General shape « Acentrella -like»: flattened ventrally, with enlarged legs and shortened abdomen. Head, pronotum and mesonotum with protoptera densely covered with placoid sensilla ( Fig. 45 ). Head wide; frons between antennae bases flat; arms of frontal suture shallowly arched ( Figs 45 , 55 ). Labrum with regular submarginal row of 7–8 thick pointed setae on each side ( Fig. 49 ). Each mandible with incisor and kinetodontium completely fused together forming plate widened distally and vaulted ventrally; prostheca of right mandible slender and pointed; each mandible without setae on median margin between prostheca and mola ( Figs 46–47 ). Maxillary palp without incision ( Fig. 51 ). Hypopharynx with dense apical tuft of long spines ( Fig. 71 ). Labium ( Fig. 50, 52 ) with glossae slightly shorter and much narrower than paraglossae; paraglossa swollen in middle. Glossa terminated by single long, widened proximally and pointed seta; its median margin with 2 setae near apex; lateral margin with 2 more slender setae near apex; other setae absent. 2nd and 3rd segments of labial palp fused together, wide, without muscle which initially moves 3rd segment. Pronotum unusually long, with length exceeding ½ width ( Fig. 59 ). Outer side of femur with regular row of long stout setae; each seta parallelsided, with apex dentate ( Fig. 69 ); two setae near apex of femur shorter, with apices more smooth ( Fig. 66 ). Outerdorsal side of tibia with regular row of stout setae; each seta terminates by slender process and bears numerous fine short processes on its side directed toward distal end of tibia ( Fig. 68 ). Patella-tibial suture of all legs modified to a shallow groove running along tibia close to row of stout setae and terminates near tibial apex ( Figs 66–68 ). Claw with distal denticle enlarged, other denticles smaller; two setae arise by sides of distal denticle—one on anterior and another on posterior side of claw ( Fig. 58 ). Abdominal terga with scales in small semicircular nests lacking operculae ( Fig. 65 ). Posterior margin of each tergum I–X with irregular, minute, pointed denticles in lateral parts and wider denticles in middle part ( Figs 60, 64 ). Abdominal sterna without scales and posterior denticles, each with one pair of small denticulate fields near anterior-lateral corner ( Fig. 61 ). Tergalii I absent; tergalii II–VII unusually small, not longer than ½ of tergum length; anterior and posterior costae developed only on proximal part of tergalius; trachea not visible ( Figs 53 , 60, 62 ). Paraprocts without distinct posterior margins; each paraproct with one or two denticles ( Fig. 72 ). Paracercus reduced to several segments (3, 10 and 13 segments in three specimens examined), without lateral swimming setae or their vestiges ( Fig. 75 ); ventral side of paracercus with fields of dense minute spines adjacent to posterior margin of each segment ( Fig. 74 ); dorsal side with flat triangular denticles on posterior margins of segments ( Fig. 73 ). Cerci without swimming setae or their vestiges; distal margin of each segment with flat triangular denticles ( Figs 73, 74 ).

Subimago. CUTICULAR COLORATION: Mesonotum light brown, with medioparapsidal suture, sublateroscutum and lateral area of scutellum contrastingly colorless (as in Fig. 18 ). Thoracic sterna and pleura with light membranes and brown sclerites; posterior part of postsubalar sclerite without dorsal convexity. Wings gray.

HYPODERMAL COLORATION: In both sexes, abdominal terga uniformly dark brown with irregular small light dots; sterna light ( Fig. 70 ).

TEXTURE: On fore leg of male subimago, 1st tarsomere covered with pointed microlepides; 2nd–4th tarsomeres entirely covered with blunt microlepides; 5th tarsomere covered with pointed microlepides (as in Figs 6–8 ). On middle and hind legs of both sexes 1st+2nd, 3rd and 4th tarsomeres covered with blunt microlepides; 5th tarsomere covered with pointed microlepides (as in Figs 11–17 ). Fore leg of female (4-segmented—see characteristics of Indobaetis ) with the same texture as on middle and hind legs ( Fig. 4 ).

Imago, male. Unknown. Judging by male subimago, has following features. Turbinate eyes unusual in shape, with facetted surface much narrower than base ( Fig. 57 ); in subimago, turbinate eyes uniformly dark red. Abdominal terga uniformly dark brown with irregular small light dots; sterna light ( Fig. 70 ).

GENITAL STRUCTURE ( Fig. 54 ): Unpaired sterno-styligeral muscle present. Gonovectes weak and slightly bent. Gonostylus has 1st segment not narrowed toward apex and sharply separated from 2nd segment; 3rd segment truncate.

Imago, female. Unknown. Judging by female subimago extracted from mature larva, abdominal terga uniformly dark brown with irregular small light dots (as in male—Fig. 70); thoracic and abdominal sterna light ocher.

Eggs. Unknown.

Dimension. Fore wing length 2.5 mm.

Distribution and habitat. Southern India (Western Ghats). Larvae were collected in a small forest stream, where water level is extremely low in dry season.

Comparison. Larva of Indobaetis microfolius sp.n. differs from other Indobaetis and most other Baetidae by completely fused 2nd and 3rd segments of labial palp ( Fig. 52 ), longitudinal patella-tibial suture ( Fig. 67 ) and very small tergalii ( Fig. 53 ). From other Indobaetis it differs also by absence of transverse row of setae on glossae ( Fig.

50), absence of posterior prolongation of paraproct ( Fig. 72 ), Acentrella -like habitus, vestigial paracercus with modified armature ( Fig. 74 ), loss of primary swimming setae on cerci and other characters.

Male subimago (and probably imago) of I. microfolius sp.n. differs from I. costai and most other Baetidae by turbinate eyes narrowing apically ( Fig. 57 ). From I. costai it differs also by entirely dark abdominal terga ( Fig. 70 ) and shape of gonostyli.

Figures

FIGURES 40 – 45. Indobaetis spp., larvae. 40, I. starmuehlneri, head; 41 – 44, I. costai: 41, head; 42, claw of left leg, ventral view; 43, exuviae of right half of pronotum and mesonotum; 44, exuviae of frons. 45, I. microfolius sp. n., the same.

FIGURES 46 – 52. Indobaetis microfolius sp. n., larval mouth parts. 46, left mandible; 47, 48, right mandibles; 49, labrum; 50, glossa (dorsal view); 51, maxilla (dorsal view); 52, half of labium (ventral view). Abbreviations: ds 1 and ds 2, first and second dentisetae (52, holotype).

FIGURES 53 – 59. Indobaetis microfolius sp. n. 53, margins of larval abdominal segments IV – VI with tergalii; 54, genitals of male subimago (sterno-styligeral muscle and styliger-gonostylar muscles shown by interrupted lines); 55, larval head; 56, wing venation; 57, head of male subimago; 58, larval claw, posterior view; 59, exuviae of right half of larval pronotum and mesonotum (53, 54, 56 – 58, holotype). Abbreviations: gs 1 – gs 3, 1 st – 3 rd segments of gonostylus; m. s, median sterno-styligeral muscle; us, unistyliger.

FIGURES 60 – 65. Indobaetis microfolius sp. n. 60, abdominal sterna and terga VI – VII; 61, denticles on anterior-lateral corner of sternum VII; 62, tergalius VII (ventral view); 63, surface of tergum VI; 64, 65, posterior margin and scales on abdominal tergum VI.

FIGURES 66 – 70. Indobaetis microfolius sp. n. (holotype). 66 – 69, details of larval middle leg; 70, abdominal sterna and terga of male subimago, spread on slide.

FIGURES 71 – 75. Indobaetis microfolius sp. n. 71, hypopharynx and superlingua; 72 – 75, abdominal segment X with paracercus and bases of cerci: 72, 74, 75, ventral view; 73, dorsal view.

FIGURES 18 – 22. Indobaetis costai. 18, subimaginal exuviae of left half of mesonotum; 19, subimaginal exuviae of left subalar sclerite, postsubalar sclerite and lateropostnotal crest; 20, abdominal segments I – VI of male imago, spread on slide; 21, genitals of male imago (intersegmental ventral muscles taken away and unpaired sterno-styligeral muscle visible though integument); 22, part of larval fore leg.

FIGURES 5 – 10. Indobaetis costai. 5, fore tarsus of female subimago; 6 – 8, fore tarsus of male subimago and its enlarged base; 9, scales on abdominal tergum; 10, apex of left maxilla, dorsal view. Abbreviations: ds 1 and ds 2, first and second dentisetae.

FIGURES 11 – 17. Indobaetis costai, middle leg of subimago and its details. Abbreviations: bml, blunt microlepides; mt, microtrichiae; pml, pointed microlepides; t 1 & 2, fused first and second tarsomeres; t 3 – t 5, tarsomeres 3 – 5.

FIGURES 1 – 4. Fore tarsus of female. 1, female subimago of Nigrobaetis (Takobia) muticus; 2, female subimago of Indobaetis costai; 3, imago of the same specimen; 4, female subimaginal tarsus of Indobaetis microfolius sp. n. visible through larval cuticle. Abbreviations: t 1 – t 5, tarsomeres 1 – 5; t 1 & 2, fused first and second tarsomeres.