Cincticostella richardi Martynov & Palatov, 2019

Martynov, Alexander V., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G., Chandra, Kailash, Palatov, Dmitry M., Sinha, Bikramjit & Jacobus, Luke M., 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 : 149-154

Cincticostella richardi Martynov & Palatov , sp. nov.

( Figs 1–25 )

Larva. Late instar: body length 8.0– 8.2 mm; caudal filaments 4.2–5.4 mm. Body yellowish-brown to brown. Body robust ( Fig. 1 ), all body surfaces, labrum, mandibles, labium and gills densely covered with large scales sockets and small scales in some of them ( Figs 2, 4–9, 13 , 20 ).

Head: With two pairs of small, blunt protuberances. Genae moderately developed ( Fig. 2 ). Mouthparts: Labrum wide, angles rounded ( Fig. 9 ); anteromedian emargination shallow; dorsal surface densely covered with long, hair-like setae; anterior margin with numerous feathered and hair-like setae; ventral surface with numerous long, stout, hair-like setae. Mandibles with numerous long, hair-like setae on dorsal and lateral surfaces ( Figs 7, 8 ). Right mandible with trifurcated outer incisor, and bifurcated inner incisor; mandible with row of 9 long, stout, hairlike setae under mola and bunch of short, hair-like setae above; prostheca consisting of bunch of hair-like setae. Outer incisor apex on left mandible with three distinct denticles and one small, blunt denticle; inner incisor (kinetodontium) of left mandible 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; surfaces of lingua covered with hair-like and fine setae mainly in apical part ( Fig. 10 ). Rows of short, pointed, stout setae (up to 7) present on lingua surface near base; these rows subparallel to lateral margins. Maxilla with two dentisetae with inner margins serrate. Apex and apical part of maxilla surface with numerous long, stout, hair-like setae, some of these setae with serrated inner margins; galea-lacinia with long, stout, hair-like setae on inner margin and group of 8 long, feathered, stout setae at surface near base ( Fig. 12 ). Maxillary palp 3-segmented, segment II with few, relatively long, hair-like setae; segment III short, distinctly narrowed and pointed ( Fig. 11 ); segmentation weakly developed. Labium with rounded glossae; dorsal surface of glossae and apexes of paraglossae covered with long, stout, hair-like setae ( Fig. 13 ). Inner margins of paraglossae subparallel to longitudinal axis of body, held tightly against glossae. Whole ventral surface of labium, including mentum and submentum, covered with middle-sized and short, hair-like setae. Labial palp 3-segmented; segment I and segment II subequal in length, covered with long, hair-like setae; segment II with several long, stout, hair-like setae on dorsal surface and outer margin; segment III slightly elongated, rounded apically (length/width ratio = 1.53–1.78) ( Fig. 13 ), apex covered with numerous fine setae.

Thorax: Pronotum expanded laterally, with anterolateral angles projecting forward and laterally ( Figs 4–6 ). Anterolateral projections of mesothorax blunt and not notched, with margins usually subparallel to lateral aspect of body ( Figs 3, 4 ). Thoracic surface with fine and short, hair-like setae; with small, indistinct ridges and tubercles and small, blunt posterior projections between forewing pads ( Figs 1, 4 ).

Femora of all legs moderately flattened (length/width ratio = forefemur 2.5–2.6; middle femur 2.4–2.5; hind femur 2.6–2.7) and with longitudinal ridge, especially visible on mid- and hindfemora ( Figs 14–16 ). All femora longer than tibiae, and tibiae longer than tarsi. Apical half of outer margin of forefemur with serration ( Fig. 14 ), apexes of chalazae with long or short, stout setae with rounded or bluntly pointed apexes. Additionally, whole outer margin covered with irregular row of long, hair-like setae. Inner margin of forefemur serrate or with several (2–7) distinct chalazae and stout setae (as on outer margin) in central part; several long, pointed, stout setae in basal part of margin; short, hair-like setae along entire length of margin. Surface of forefemur densely covered with solitary, fine setae, middle-sized, hair-like setae, several pointed, stout, hair-like setae and middle-sized and short, stout setae with rounded, pointed or bluntly pointed apexes. Stout setae situated mainly near outer and inner margins. Central part of forefemur with few, rounded or bluntly pointed apically, stout setae, often forming chalazae ( Figs 14, 18 ). Dorsal surface of fore tibia with hair-like setae (solitary and in bunches) and short row of several long, spine-like setae or long, stout, hair-like setae. Outer margins of fore tibia and tarsus 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 elongated, feathered, stout setae. Inner margin of fore tarsus with hair-like setae and dense row of stout, hair-like setae, spine-like and feathered, stout setae. Outer and inner margins of mid- and hindfemora with distinct, but not deep, serration; such serration more obvious than on forefemur ( Figs 14–16, 20 ). Chaetotaxy of mid- and hindfemora similar to foreleg, except for presence of several stout setae with rounded or bluntly pointed apexes in basal part of femora. Outer margin of midfemur with moderately developed apical projection, hindfemur with distinct projection ( Figs 15, 16 ). Outer and inner margins of mid- and hind tibiae with hair-like setae (solitary and in bunches) and row of elongated, spine-like setae; on outer margins spine-like setae more numerous. Distal ends of inner margins of tibiae each with group of spine-like setae and elongated, feathered stout setae. Inner margins of mid- and hind tarsi with hair-like setae (solitary and in bunches) and row of stout, hairlike setae and spine-like setae; outer margins of these tarsi with hair-like setae only.

Tarsal claws of all legs distinctly hooked ( Figs 17, 19 ), with 2 subequal denticles (if third denticle present, always smaller and situated close to others) and 3 subapical setae.

Abdomen: Dorsal surface and posterior margins of terga covered only with hair-like setae; stout setae absent. Pairs of projections present on terga II–X, with those on terga II–IV, IX and X smaller than others; those on terga V–VIII more developed ( Fig. 21 ). Paired tergal projections not bifurcated; those of terga II–VII pointed; those of terga VIII elongated, bluntly pointed; those of tergum IX very small and rounded; those of tergum X bluntly pointed and bigger than those of tergum IX. Lateral projections of segment IX wide and not pressed against segment X ( Figs 1 , 21 ). Posterolateral projections of segments III–IX present and distinct ( Fig. 21 ).

Lamellate gills ( Figs 22–25 ) dorsal surfaces and margins covered with relatively long, hair-like setae; gill III without medial transverse band of weakened membrane; dorsal lamella of gill V somewhat longer than dorsal lamellae of gills III–IV; 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 the late Dr. Richard K. Allen ( USA), who described the subgenus Rhionella .

Diagnosis. The new species can be easily distinguished from other representatives of the genus by the following combination of characters: (i) genae are moderately developed; (ii) anterolateral angles of pronotum with projections directed forward and laterally; (iii) projections of mesothorax not notched; (iv) forefemur with distinct serration on inner and outer margins; (v) dorsal surface of forefemur usually with few knob-like projections (chalazae) bearing stout setae; (vi) middle and hind femora moderately flattened; (vii) outer and inner margins of mid- and hindfemora with shallow serration; (viii) outer margin of middle femur with moderately developed apical projection; (ix) all pairs of abdominal tergal projections not bifurcated; (x) lateral projections of abdominal segment IX wide and not pressed against segment X ( Figs 1 , 21 ); (xi) tarsal claw with 2 subequal denticles (see details above).

Distribution. Known only from India ( Fig. 153 ).

Habitat. Larvae of Cincticostella richardi sp. nov. inhabit large (from 20–100 m wide) mountain rivers (Alaknanda and Pindar Rivers) ( Figs 147, 148 ) which are typical for the low mountain zone (up to 1000 m a.s.l.) of the Great Himalayan Range within India (Uttarakhand State). These rivers are characterized by low water temperature (9–14°C at the time of sampling), high average current velocity (from 0.3–1.5 m /s) and mainly stonepebble bottom with significant silting. Larvae were sampled under the stones and also from roots, branches and other substrates near the banks, mainly in places with current velocity from 0.3–0.6 m /s.

It should be noted that large rivers of the mentioned low mountain zone are experiencing significant anthropogenic pressures, especially organic pollution. Investigated rivers can be classified as alpha- or betamezosaprobic. As a result, most oxyphillic species, including Cincticostella richardi sp. nov., survived only in mountain rivers with high current velocity and rapids.

Type material. INDIA: Holotype: larva, Uttarakhand State, Chamoli district, Pindar River (2 km above of the Karnaprayag town ), 30.251625 N, 79.229203 E, h ~ 780 m a.s.l., 04-II-2011, D.M. Palatov—IN Indi 4 Cinric / 1. Paratypes: INDIA: 3 larvae (one mature larva in slide number 645), same data as holotype—IN Indi 4 Cinric /2; 1 larva, Uttarakhand State , Chamoli district , Alaknanda River (700 m above mouth of the Pindar River ), 30.267728 N, 79.220931 E, h ~ 800 m a.s.l., 5-II-2011, D.M. Palatov and M.V. Chertoprud—IN Indi 6 Cinric .

Figures

FIGURE 153. Map of distribution of the Cincticostella insolta complex representatives: a.—Cincticostella richardi sp. nov.; b.—Cincticostella sivaramakrishnani sp. nov.; c.—Cincticostella ranga sp. nov.; d.—Cincticostella bifurcata Xie, Jia, Chen, Jacobus & Zhou, 2008; e.—Cincticostella insolta (Allen, 1971); f.—Cincticostella braaschi Jacobus & McCafferty, 2008; g.— Cincticostella femorata (Tshernova, 1972). Note: Distributions of C. insolta and C. femorata in mainland China mentioned by Xie et al. 2009 could not be given on the map, due to insufficient data.

FIGURES 1–6. Larva of Cincticostella richardi sp. nov., holotype (1) and paratypes (2–6): 1.—dorsal habitus; 2.—head; 3.— projection of mesothorax; 4.—dorsal view of thorax; 5–6.—anterolateral projections of pronotum. Scale bar: 1–4.—1.0 mm; 5, 6.—0.5 mm.

FIGURES 7–13. Larva of Cincticostella richardi sp. nov., paratypes: 7, 8.—mandibles; 9.—labrum; 10.—hypopharynx; 11.— maxillary palp; 12.—apical part of maxilla; 13.—labium. Scale bar: 7–10, 13.—0.5 mm; 11.—0.1 mm; 12.—0.25 mm.

FIGURES 14–20. Larva of Cincticostella richardi sp. nov., paratypes: 14.—forefemur; 15.—middle femur; 16.—hind femur; 17, 19.—claws; 18.—knob with stout setae on dorsal surface of forefemur; 20.—outer margin of hind femur. Scale bar: 14– 16.—1.0 mm; 17, 19.—0.25 mm; 18.—0.1 mm; 20.—0.5 mm.

FIGURES 21–25. Larva of Cincticostella richardi sp. nov., paratypes: 21.—abdominal terga, dorsal view; 22–25.—gills III– VI. Scale bar: 21.—1.0 mm, 22–25.—0.5 mm.

FIGURES 147–152. Collection localities of Cincticostella richardi sp. nov. (147, 148), Cincticostella sivaramakrishnani sp. nov. (149, 150) and Cincticostella ranga sp. nov. (151, 152): 147.—Alaknadra River (800 m a.s.l.); 148.—Pindar River (780 m a.s.l.) (C. richardi sp. nov. type locality); 149, 150.—Modi River (1550 m a.s.l.) (C. sivaramakrishnani sp. nov. type locality); 151.—Talle Valley (2370 m a.s.l.) (C. ranga sp. nov. type locality); 152.—Ranga River (625 m a.s.l.).