Cincticostella sivaramakrishnani Martynov & Palatov

Martynov, Alexander V., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G., Chandra, Kailash, Palatov, Dmitry M., Sinha, 2019, Review of the Cincticostella insolta (Allen, 1971) complex (Ephemeroptera: Ephemerellidae), with description of three new species from northern India and Nepal, Zootaxa 4551 (2), pp. 147-179: 154-160

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Cincticostella sivaramakrishnani Martynov & Palatov

sp. nov.

Cincticostella sivaramakrishnani Martynov & Palatov  , sp. nov.

( Figs 26–52View FIGURES 26–31View FIGURES 32–38View FIGURES 39–46View FIGURES 47–52)

Larva. Body length 5.1–6.9 mm; caudal filaments length 4.5–6.3 mm. Body yellowish-brown. Body robust ( Fig. 26View FIGURES 26–31); all body surfaces, labrum, mandibles, labium and gills densely covered with large scales sockets and small scales in some of them ( Figs 27–34, 38View FIGURES 26–31View FIGURES 32–38, 40, 41, 46View FIGURES 39–46).

Head: With two pairs of small, blunt protuberances. Genae moderately developed ( Fig. 27View FIGURES 26–31). Mouthparts ( Figs 32–38View FIGURES 32–38): Labrum wide, angles rounded ( Fig. 34View FIGURES 32–38); anteromedian emargination shallow, dorsal surface densely covered with long, hair-like setae; ventral surface with numerous, long, stout, hair-like setae; anterior margin with numerous feathered setae and hair-like setae. Mandibles with numerous, long, hair-like setae on dorsal and lateral surfaces ( Figs 32, 33View FIGURES 32–38). Right mandible with row of 6–9 long, stout, hair-like setae under mola and bunch of short, hair-like setae above; outer incisor apex trifurcated, inner incisor (kinetodontium) bifurcated; prostheca apparently consisting of bunch of hair-like setae. Left mandible: outer incisor apex with three distinct denticles and one small, blunt denticle; inner incisor (kinetodontium) with two distinct, central denticles and one small, blunt, lateral denticle; prostheca consisting of protuberance with bunch of hair-like setae. Rounded apexes of superlinguae with long, stout, hair-like setae; surface of lingua with hair-like and fine setae, mostly in apical part ( Fig. 35View FIGURES 32–38). Rows of up to 7 short, pointed, stout setae on surface of lingua near base, subparallel to lateral margins. Maxillary palp ( Fig. 36View FIGURES 32–38) 3-segmented, with up to 8 long, hair-like setae; segmentation weakly developed; segment III short, bluntly pointed, with few fine setae on apex. Maxilla with two dentisetae with serrated inner margins; apex and apical part of maxilla surface with numerous, long, stout, hair-like setae, some setae with serrated inner margins; inner margin of galea-lacinia with row of long, stout, hair-like setae; 6–9 different-sized, feathered, stout setae present on galea- lacinia surface near base ( Fig. 37View FIGURES 32–38). Glossae rounded ( Fig. 38View FIGURES 32–38); dorsal surface of glossae and apexes of paraglossae covered with long, stout, hair-like setae. Inner margins of paraglossae subparallel to longitudinal axis of body, held tightly against glossae. Ventral surface of labium (including mentum and submentum) mostly covered with short, hair-like setae. Labial palp 3-segmented; segment I and segment II subequal in length, covered with long, hair-like setae; dorsal surface of segment II and outer margin of segment I with several spine-like setae and long, stout hairlike setae; segment III slightly elongate, with length 1.75–1.79× width at base, apex covered with numerous fine setae.

Thorax: Dorsal surface with small, indistinct ridges and tubercles, and small, blunt posterior projections between forewing pads ( Figs 26, 29View FIGURES 26–31). Anterolateral angles with small projections directed forward ( Figs 29–31View FIGURES 26–31); anterolateral projections of mesothorax rounded and not subparallel to lateral aspect of body, though these projections may appear subparallel after slide-mounting ( Figs 26, 28, 29View FIGURES 26–31).

Femora of legs moderately flattened (length/width ratio = forefemur 2.1–2.3; middle femur 2.0–2.1; hind femur 2.1–2.2); all femora with longitudinal ridges ( Figs 39–41View FIGURES 39–46). Femora longer than tibiae, and tibiae longer than tarsi. Outer and inner margins of forefemur without serration (sometimes only 1 or 2 small chalazae along outer margin) ( Figs 39, 45View FIGURES 39–46), with only hair-like setae and few stout setae with rounded apexes. Dorsal surface of forefemur covered with hair-like setae; central part of dorsal surface with few chalazae bearing stout setae with rounded apexes ( Figs 39, 43View FIGURES 39–46); few stout setae with rounded or bluntly pointed apexes also located near outer and inner margins. Surface of fore tibia with hair-like setae (solitary and in bunches) and short row of spine-like setae. Outer margins of fore tibia and tarsal segments with short, hair-like setae (solitary and in bunches). Inner margin of fore tibia with hair-like setae and sparse row of spine-like setae; distal end of margin with group of spine-like setae and elongated, feathered, stout setae. Inner margin of fore tarsus with hair-like setae and dense row of stout, hairlike setae, spine-like setae and feathered, stout setae. Outer margins of mid- and hindfemora with shallow serration ( Figs 40, 41View FIGURES 39–46), with apex of each weak protuberance bearing stout setae with rounded or bluntly pointed apexes, varying in length ( Fig. 46View FIGURES 39–46). Inner margins of mid- and hindfemora without serration. Chaetotaxy of surface of mid- and hindfemora similar to forefemur, but lacking stout setae. Outer margin of midfemur without apical projection; hindfemur with distinct apical projection ( Figs 40, 41View FIGURES 39–46). Middle tibia: outer margin with hair-like setae (solitary and in bunches); inner margin with row of elongated, spine-like setae and hair-like setae; surface with hair-like setae only. Hind tibia: Outer and inner margins with hair-like setae (solitary and in bunches) and row of elongated, spinelike setae. Distal ends of inner margins of mid- and hind tibiae with groups of spine-like setae and elongated, feathered, stout setae. Mid- and hind tarsi inner margins with hair-like setae (solitary and in bunches) and rows of stout, hair-like setae and spine-like setae; outer margins with hair-like setae only.

Tarsal claw distinctly hooked, with 3–7 denticles (largest denticle in middle) ( Figs 42, 44View FIGURES 39–46) and 3 subapical setae.

Abdomen: Dorsal surface and posterior margins of terga covered only with hair-like setae; stout setae absent. Terga II–X with pairs of projections; projections on terga II–IV and X smaller than others; projections on terga V– IX more robust ( Figs 47, 48View FIGURES 47–52). Paired projections on tergum VII sometimes bifurcated apically (visible in lateral view); paired projections on tergum VIII always bifurcated in this way; lower edge of paired projections on terga V and VI elongated, but without bifurcation notch ( Fig. 48View FIGURES 47–52). Paired projections on terga II–VII and X pointed dorsally; paired projections on terga VIII and XI blunt. Posterolateral projections present on segments III–IX, poorly developed on segments III–V, most strongly developed on segments VIII and IX ( Fig. 47View FIGURES 47–52).

Dorsal surface and margins of lamellate gills ( Figs 49–52View FIGURES 47–52) covered with relatively long, hair-like setae; gill III without medial transverse band of weakened membrane; dorsal lamella of gill VI somewhat longer than that of gills III–V; gill VII very small and entirely covered by gill VI.

Caudal filaments subequal in length, with elongated, apically rounded, stout setae and hair-like setae at articulations.

Adults. Unknown.

Etymology. The new species is named in honor of our co-author Dr. Kumbakonam G. Sivaramakrishnan, who has contributed significantly to the study of mayflies from the Indian zoogeographical subregion over the course of his career.

Diagnosis. The new species can be distinguished easily from other representatives of the genus by the following combination of characters: (i) genae moderately developed; (ii) anterolateral angles of pronotum with projections directed forward; (iii) anterolateral projections of mesothorax not notched; (iv) forefemur without serration along inner and outer margins (occasionally with one or two chalazae on outer margin); (v) dorsal surface of forefemur usually with chalaza bearing few stout setae; (vi) mid- and hindfemora moderately flattened; (vii) outer margins of mid- and hindfemora with shallow serration, their inner margins without serration; (viii) middle femur without apical projection; (ix) paired projections on tergum VIII, and sometimes tergum VII, bifurcated apically; (x) tarsal claw with 3–7 denticles, one of the middle denticles being distinctly larger.

Distribution. Known only from Nepal ( Fig. 153View FIGURE 153).

Habitat. Larvae of C. sivaramakrishnani  sp. nov. inhabit small rivers in the middle mountain zone (1400– 1800 m a.s.l.) of Annapurna massif, one of the biggest spurs of the Great Himalayan Range within Central Nepal ( Figs 149, 150View FIGURES 147–152). Larvae inhabit the rhithral zone of mountain rivers and streams that are 3–12 m wide, with stony bottoms, high current velocities and almost no anthropogenic pollution. Water temperatures during the collecting of material ranged from 9–12°C. Larvae were collected from the undersides of stones and pebbles in places with current velocities ranging from 0.3–0.8 m /s.

Type material. NEPALGoogleMaps  : Holotype: larva, Gandaki Zone, Kaski District, Modi River (near Jhinu village   GoogleMaps), 28.409494 N, 83.826894 E, h ~ 1550 m a.s.l., 16-III-2007, M.V. Chertoprud—IN Nepa  10Cinsiv/3. Paratypes: 12 larvae (one larva in slide number 652), same data as holotype—IN Nepa  10 Cinsiv /1–2GoogleMaps  ; 2 larvae (one in slide number 646), Gandaki Zone, Kaski District, Modi Khola River (1 km below New Bridge village ), 28.393611 N, 83.825833 E, h ~ 1400 m a.s.l., 31-I-2014, V.V. Marinskiy—IN Nepa  6CinsivGoogleMaps  ; 9 larvae, Bagmati zone, Kathmandu District, Shivapuri Nagarjun National Park, western source of the Budhanil ( Bhoti ) Khola River (1 km Northwards of the Phedigaun village ), 27.798611 N, 85.373611 E, h ~ 1600 m a.s.l., 20-III-2007, M.V. Chertoprud—IN Nepa  8Cinsiv/1–3GoogleMaps  ; 6 larvae (one larva in slide number 651), Gandaki Zone, Kaski District, Chomrong Khola River (near Chomrong village ), 28.407739 N, 83.816450 E, h ~ 1800 m a.s.l., 16-III-2007, M.V. Chertoprud—IN Nepa  9Cinsiv/1–2GoogleMaps  .