Indobaetis Müller-Liebenau & Morihara 1982

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 : 214-215

Indobaetis Müller-Liebenau & Morihara 1982

( Figs 2–75 )

Type species: Indobaetis costai Müller-Liebenau & Morihara 1982 .

General characteristic given to Indobaetis by Müller-Liebenau & Morihara (1982) should be modified as the following.

Apomorphies of Indobaetis .

(1) Each mandible has incisor and kinetodontium completely fused together forming an integral plate with cutting edge widened, evenly dentate and vaulted ventrally, so that its part corresponding to incisor is less projected medially than its part corresponding to kinetodontium ( Figs 46–48 ; Müller-Liebenau & Morihara 1982: Figs 1 f, 2f).

(2) Prostheca of right mandible is slender and pointed, not bifurcate ( Figs 47, 48 ; Müller-Liebenau & Morihara 1982: Figs 1 f, 2f) (see Discussion, 2.4).

(3) Maxilla has 2 dentisetae: 1st dentiseta (most distal) is thick and adjacent to maxillary canines (as in many other Baetidae ); 2nd dentiseta is sharply arched and pressed to the first dentiseta, so that its middle part is hidden between the first dentiseta and the canines; 3rd dentiseta is absent; setae of median-dorsal row form a compact bunch, basally adjacent to the second dentiseta and distally diverging from it ( Figs 10 , 51 ). In other Baetidae three dentisetae, initial for Tridentiseta Kluge et al. 1995, are retained ( Kluge 2004: Figs 28 B, D).

(4) Larval tibia has a regular row of stout setae on outer margin, different from setae of a regular row on outer margin of femur ( Figs 22 , 67, 68 ).

(5) Larval claw has distal denticle enlarged, with at least one strong seta posteriad of it ( Figs 42 , 58 ) (see Discussion, 2.7).

(6) Hind wings are absent; larva has no vestiges of hind protoptera ( Müller-Liebenau & Morihara 1982: Figs 1 i, 2g).

(7) Tergalii of first pair are lost, only 6 pairs of tergalii are present.

(8) In mature larva buds of subimaginal gonostyli are folded by « Labiobaetis - type » ( Figs 28, 29 ); this character is known only for I. costai (see Discussion, 2.10)

(9) On fore leg of female subimago and imago 1st tarsomere is completely fused with 2nd tarsomere, so the tarsus is 4-segmented ( Figs 2–5 ), like tarsi of middle and hind legs ( Fig. 11 ). This character is known for I. costai and I. microfolius sp.n. In most other Baetidae fore tarsus of female subimago and imago has 1st tarsomere well separated from 2nd tarsomere ( Fig. 1 ) (see Discussion, 2.12).

Character of Indobaetis of unclear phylogenetic polarity.

(10) In subimago, 1st and 5th tarsomeres are covered mainly with pointed microlepides, other tarsomeres mainly with blunt microlepides ( Figs 5–8 , 11–17 ); this character is known for I. costai and I. microfolius sp.n. (see Discussion, 2.13)

Plesiomorphy of Indobaetis .

(11) Sterno-styligeral muscle is retained ( Figs 21 , 24 , 54 ); this character is known for I. costai and I. microfolius sp.n. (in contrast to Labiobaetis, Baetosternata and some other taxa, whose sterno-styligeral muscle is completely lost—see Discussion, 2.11).

Characters variable among species of Indobaetis . Larval habitus varies from Nigrobaetis -like in I. costai and I. starmuehlneri (i.e., with head bowed ventrally, head and thorax laterally compressed, three caudalii and their primary swimming setae well developed) to Acentrella -like in I. microfolius sp.n. (i.e., head and thorax flattened ventrally, paracercus reduced, and swimming setae lost). Frons varies from narrow and keeled to wide and flat ( Figs 40, 41 , 55 ). Maxillary palp, being 2-segmented (as in all Baetungulata), has 2nd segment either incised (in I. costai ), or not (in other species—Fig. 51). Transverse row of fine setae on glossa is either present (in I. costai and I. starmuehlneri ), or absent (in I. microfolius sp.n. — Fig. 50 ). Labial palp either has structure usual for Baetidae (in I. starmuehlneri ), or has 2nd segment unusually narrowed (in I. costai ), or has 2nd and 3rd segments completely fused together and lacking muscle (in I. microfolius sp.n. — Fig. 52 ). Patella-tibial suture, being equally developed on all legs (that is characteristic for Anteropatellata), either has normal shape (in I. costai and I. starmuehlneri — Fig. 22 ), or is smoothed and stretches along tibia (in I. microfolius sp.n. — Fig. 67 ). Larval paraproct either has tongue-like denticulate prolongation of inner posterior edge (in I. costai and I. starmuehlneri — Figs 38, 39 ), or with posterior margin non-expressed (in I. microfolius sp.n. — Fig. 72 ).

Distribution. Southern India and Sri Lanka.

Species composition. 3 species: Indobaetis costai Müller-Liebenau & Morihara 1982 , I. starmuehlneri Müller-Liebenau & Morihara 1982 and I. microfolius sp.n.

Comments. Selva-kumar et al. (2012) described Indobaetis michaelohubbardi based on larvae from southern India. Subsequent reexamination of the type specimens reveals that this species has hind protoptera and other characters of Baetis s.str. (K.G. Sivaramakrishnan, personal communication). In the photo (Selva-kumar et al. 2012: Fig. 34 ) three maxillary dentisetae are visible, that allows to exclude this species from Indobaetis . According to the photos (Selva-kumar et al. 2012: Figs 29–38 ) this species belongs to subgenus Tenuibaetis Kang & Yang (in Kang et al.) 1994 of the genus Baetis s.str. So, the valid binomen is Baetis michaelohubbardi (Selva-kumar et al. 2012), comb.n.

Figures

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.

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 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 23 – 29. Indobaetis costai. 23 – 25, male imago: 23, wing; 24, genitals (ventral view, muscles of middle and left parts shown by interrupted lines); 25, head and dorsal outline of pronotum and anteronotal protuberance, lateral view. 26, head of female imago, dorsal view. 27, subimaginal exuviae of right unistyliger and gonostylus; 28, subimaginal genitals developing under larval cuticle; 29, the same at earlier phase. Abbreviations: gs 1 – gs 3, 1 st – 3 rd segments of gonostylus; m. s, median sternostyligeral muscle; m. IX – X, intersegmental ventral muscles going from base of 9 th abdominal segment to base of 10 th abdominal segment; us, unistyliger.

FIGURES 30 – 35. Indobaetis costai, eggs and their enlarged micropilar areas.

FIGURES 36 – 39. Posterior view on 10 th abdominal segment (cerci and paracercus taken away). 36, Nigrobaetis (Takobia) maxillaris; 37, undescribed species of Papuanatula from Baliem Valley (Papua province of Indonesia); 38, 39, two specimens of Indobaetis costai.

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.