Cincticostella wangi Selvakumar, Martynov & Subramanian, 2021

Martynov, Alexander V., Selvakumar, C., Palatov, Dmitry M., Subramanian, K. A., Sivaramakrishnan, K. G., Vasanth, M. & Jacobus, Luke M., 2021, Overview of Indian and Nepali representatives of the Cincticostella nigra (Ueno, 1928) complex (Ephemeroptera, Ephemerellidae), with discussion about Cincticostella Allen, 1971 species complexes, ZooKeys 1040, pp. 123-166 : 123

Cincticostella wangi Selvakumar, Martynov & Subramanian sp. nov. Figs 20 , 21

Description.

Larva. Body length 6.0-7.7 mm. Caudal filaments length 5.0-5.5 mm. Body colour yellowish-brown (Fig. 20A ).

Head: Ocelli, clypeus dorsal surface and vertex without tubercles and ridges (Fig. 20B ). Genae moderately developed. Anteromedian emargination of labrum deep and wide (labrum height in emargination/maximum labrum height ratio - 0.79) (Fig. 21C ), anterior margin covered with long, thin and stout hair-like setae decreasing in length towards central notch. Dorsal surface of labrum densely covered with different hair-like setae, very short rounded scales and empty scale sockets.

Mandibles (Fig. 21A, B ) with numerous long, stout hair-like setae in central part on dorsal surfaces and outer margins. Basal half of mandibles surfaces also covered with very short scales and empty scale sockets. Planate mandible: outer incisor with three teeth, inner incisor bifurcated; row of setae under mola consists of 8-9 long, stout hair-like setae. Angulate mandible with outer incisor consisting of four teeth, second one longer than others, inner incisor with three-four teeth, central ones distinctly larger. Superlinguae of hypopharynx with numerous long, stout hair-like setae on apices; lingua with very sparse and tiny setae on dorsal and ventral surfaces, anterior margin with shallow medial concave (Fig. 21D ). Lingua surface near base bears irregular rows of short, pointed, stout setae (7-9); these rows subtransverse relative to the longitudinal axis of body. Maxilla (Fig. 21E ) with two dentisetae; apex of maxilla with bushy group of long stout and thin hair-like setae; inner margin of galea-lacinia with dense row of long, stout hair-like setae; surface galea-lacinia base with few, mainly long and middle-sized, stout hair-like setae near inner margin. Maxillary palp well-developed, 3-segmented, with segments I and II subequal in length; segment I slightly broader than segment II, segment III short and pointed. Joints between maxillary palp segments distinct (Fig. 21E ). Segments I and II with numerous long, stout hair-like setae. Labium (Fig. 21F ): ventral surface densely covered with long, stout and thin hair-like setae; dorsal surface of glossae and apices of paraglossae covered by similar setae. Labial palp 3-segmented; segments I and II flattened and subequal in length; covered with long, stout and thin, hair-like setae on ventral surfaces; segment I with group of scale sockets and scales in some of them in central part of dorsal surface. Segment III rounded apically, elongated (length/width ratio = 3.0-3.5); apex covered with few short, fine setae.

Thorax: Pronotum expended laterally, with anterolateral angles small and projecting forward (Fig. 20C ); mesonotum projections moderately developed, rounded, their outer margins not notched. Dorsal surface of thorax with scattered short, relatively strait, stout hair-like setae (Fig. 23C ); thoracic nota without ridges or projections. Paired posterior projections between fore wing pads, moderately developed, rounded, cleft between them shallow and smooth; apical parts of outer margins of projections not pressed against wing pads.

Femora of all legs flattened (length/width ratio = fore femur 2.0-2.1; middle femur 2.0-2.1; hind femur 2.0-2.2), with longitudinal ridges (Fig. 22A-C ). Femora of all legs longer than tibiae and tibiae longer than tarsi. Outer margins of all femora without apical projections.

Fore femur with distinct transverse band of numerous, mainly extremely long to middle-sized, stout setae with deeply bifurcated apices (some situated on chalazae) (Fig. 22A, D ); another part of dorsal surface with scattered hair-like setae and several pointed, stout setae in basal area and along outer margin. Outer margin of fore femur with few stout, bifurcated and pointed, stout setae; main number of the setae situated in transverse row area. Basal half of inner margin and adjacent area of dorsal surface densely covered with spine-like setae and stout hair-like setae.

Dorsal surfaces of middle and hind femora almost completely covered with different-sized, bifurcated, stout setae, some very long (Fig. 22B, C ); only longitudinal ridges and distal part of surfaces from ridges to outer margins without these stout setae. In addition, scattered hair-like setae, very small scales and empty scale sockets cover all dorsal surfaces of middle and hind femora. Outer margins of middle and hind femora covered with long, bifurcated stout setae decreasing in length towards base of femora; basal half of outer margins also with long, stout hair-like setae. Inner margins of middle and hind femora without stout setae, only with scattered hair-like setae.

Dorsal surface of all tibiae with longitudinal rows of long, bifurcated stout setae; in middle and hind legs, these rows situated closer to inner margins of tibiae. Outer margin of fore tibia with thin hair-like setae only; in middle and hind tibiae also with regular rows of long, bifurcated, stout setae.

Claws of all legs with one denticle each and several subapical setae (Fig. 22E ).

Abdomen: Paired, pointed projections present on abdominal terga II-VIII; posterior margin of tergum VIII almost straight, its protuberances very small and smooth; posterior margin of terga IX and X without projections (Fig. 22F, G ). Dorsal surfaces of terga above projections and surfaces of projections covered with short stout setae. Posterior margins of terga VIII-IX in submedian areas covered with rows of elongated, rounded apically, stout setae; posterior margin of tergum X with a discontinuous row of stout setae.

Gill III without medial transverse band of weakened membrane, dorsal lobe of gills III-V similar in shape (Fig. 22F ), gill VI diminished in size compared to gills III-V, gill VII very small and wholly covered by gill VI.

Caudal filaments subequal in length, with pointed, stout setae and hair-like setae on posterior edge of each segment, setae shorter than corresponding segment.

Adults.

Unknown.

Etymology.

The new species is named in honour of Dr. T.-Q. Wang (formerly Purdue University, USA), who contributed significantly to the study of Ephemerelloidea .

Diagnosis.

This species can be distinguished from other representatives of C. nigra complex by the following combination of characters: (i) genae moderately developed, rounded; (ii) labrum with deep and wide anteromedian emargination (Fig. 21C ); (iii) maxillary palp well-developed (Fig. 21E ); (iv) segment III of maxillary palp small, pointed; (v) prothoracic anterolateral projections small projecting forward (Fig. 20C ); (vi) mesonotum projections mesonotum projections moderately developed, rounded, their outer margins not notched (Fig. 20C ); (vii) dorsal surface of thorax with scattered short, relatively strait, stout hair-like setae (Fig. 23C ); (viii) fore femur with distinct transverse band of numerous, mainly extremely long to middle-sized, stout setae with deeply bifurcated apices (Fig. 22A, D ); (ix) tarsal claw with one denticle (Fig. 22E ); (x) paired, pointed projections present on abdominal terga II-VIII; posterior margin of tergum VIII with very small and smooth protuberances; posterior margin of terga IX and X without projections (Fig. 22F, G ); (xi) posterior margins of terga VIII-IX in submedian areas covered with rows of elongated, rounded, stout setae (Fig. 22F, G ).

Distribution.

India-China border region.

Habitat.

Cold fast-flowing stream with cobbles and gravel. The type locality of C. wangi sp. nov. is shown in Martynov et al. (2019: fig. 151).

Type material.

Holotype: India: larva, Arunachal Pradesh, Lower Subansiri District, Tale Valley, unnamed stream, 27.537201°N, 93.959883°E, h ~ 2370 m a.s.l., 14.iv.2015, Coll. K.A. Subramanian - IN 5575/H13 [ZSI]. Paratypes: India: 8 larvae, same data as holotype - IN 5575/H13 [ZSI].

Figures

Figure 20. Larva of Cincticostella wangi Selvakumar, Martynov & Subramanian, sp. nov., holotype (A) and paratypes (B and C) A habitus, dorsal view, scale bar: 2 mm B head C thorax.

Figure 21. Larva of Cincticostella wangi Selvakumar, Martynov & Subramanian, sp. nov., paratypes A planate mandible B angulate mandible C labrum D hypopharynx E apical half of maxilla F labium.

Figure 22. Larva of Cincticostella wangi Selvakumar, Martynov & Subramanian, sp. nov., paratypes A fore femur B middle femur C hind femur D stout setae of dorsal surface of fore femur E tarsal claw and tarsus F abdomen, dorsal view G terga VI-X.

Figure 23. Setae on dorsal surface of thorax of some representatives of Cincticostella nigra (Ueno, 1928) complex A dominant kind of stout setae - numerous small stout setae with divergent margins, bifurcated apices B dominant kind of stout setae - short, waved and hooked, stout hair-like setae C dominant kind of stout setae - scattered short, relatively strait, stout hair-like setae.