Dudgeodes selvakumari Martynov & Palatov sp. nov.

Figs 1, 2, 3, 4, 5, 6, 7, 8

Material examined.

Holotype: imago ♂, with corresponding larval and subimaginal exuviae, India, Uttarakhand, Mailani Range, vicinity of Garjiya village, unnamed river - left tributary of Kosi River, 29.4732°N, 79.1640°E, 430 m a.s.l., 22.v.2018, A.V. Martynov & D.M. Palatov leg., Indi 9 Telsp /1 (NMNH NASU) . Paratypes: 27 larvae, 9 larvae exuviae, 6 imagos with subimaginal exuviae, including 5♂ and 1♀), ibid., 22.v.2018, A.V. Martynov & D.M. Palatov leg., Indi 9 Telsp /2-11 (NMNH NASU) ; 51 larvae, ibid., 1-2.v.2018, A.V. Martynov & D.M. Palatov leg. - NMNH NASU (25 larvae, Indi 8 Telsp /1-11), MZL (6 larvae), Palatov’s collection (20 larvae) .

Etymology.

The new species is named in honour of Dr C. Selvakumar of India, who contributed significantly to the study of mayflies in India.

Description.

Mature larva. Body length 3.0-5.5 mm; cerci length 3.5-6.2mm. Dorsal surface of body yellowish with brown-black spots and strokes (Fig. 1A); ventral surface yellowish white, with indistinct median gray smudges on sternites (Fig. 1B).

Head dirty yellow with indistinct brown smudges. Antennae also dirty yellow, distal segments of flagellum and distal part of scapus blackish. Dorsal part of male eyes brown (Fig. 1C). Occipital and suboccipital tubercles absent. Genae moderately developed. Antennae length 1.15 times head width, flagellum with about 15 or more segments. Lateral margin of head fringed with a row of long, stout setae, forked near base and with pointed apices, a row extending from posterior margin of eyes to labrum; stout setae on posterior margin of eyes distinctly shorter (Fig. 3B). Head covered with scattered, short, hair-like setae and short, stout setae with slightly divided margins.

Mouthparts. Labrum wide and compact, width/length ratio 2.64-2.65, with smooth medial concavity on anterior margin (Fig. 2C). Dorsal surface covered with transversal band of long, stout, hair-like setae. Anterior area and margin densely covered with variously sized feathered setae.

Mandibles slender with few small setae along outer margin and one stout, hair-like seta in middle of margin. Right mandible (Fig. 2A): outer incisor composed of three teeth, one of them located remotely from others; inner incisor with two teeth; prostheca reduced, consisting of a bunch of thin setae; row of 6-8 long, stout, hair-like setae below mola and some short setae above mola. Left mandible (Fig. 2B): outer incisor with three teeth; inner incisor with two subequal teeth inserted transversely; prostheca small with a group of small setae; no setae below mola; base of mola with 2-3 small, apically pointed, stout setae.

Maxilla (Fig. 2E, F) slender, with well-developed canine, two dentisetae, and four long stout setae on inner apical part; crown with bunch of long setae; inner margin of lacinia base with 1+4 feathered, long, stout setae; maxillary palp reduced to a protuberance with single hair-like seta.

Hypopharynx with long, feathered setae on the rounded apexes of superlinguae, and very short setae on lingua (Fig. 2D).

Labial palp three-segmented, slightly constricted towards apex; articulation between segments clearly visible; segment III elongate and rounded apically, length/width at base ratio 1.9-2.2 (Fig. 2G). Outer margins of segments I and II covered with sparse, long, stout, hair-like setae; segment III with several fine setae only. Submentum well developed laterally. Glossae and paraglossae short and broad, rounded apically, their apexes densely covered with variously sized, feathered, stout setae; outer margins of paraglossae covered with long, feathered, stout setae.

Thorax. Pronotum with three pairs of tubercles: SMs, SLs, and Ls; with a few short globular stout setae; M tubercle absent (Fig. 3C-E). Lateral margins of pronotum and mesonotum with a row of long, stout setae, some of them forked (Fig. 3E). Surface of mesonotum with an MP, pair of SMMs and pair of LAs (lateral anterior tubercles) (Fig. 3C, E); these tubercles also bear a few short, stout setae with slightly divided margins.

Forefemur moderately slender, ca 2.1 times longer than wide; outer margin covered with regular row of long, stout, hair-like setae, and few thin, hair-like setae (some setae in bunches); submarginal row of setae distinct, composed of stout setae (elongate and short) with slightly divergent margins (Fig. 4D); inner margin with row of long, stout, hair-like setae. Transverse row on dorsal surface consists of about 20 long, apically pointed, stout setae (Fig. 4A). Irregular row of short, stout setae with slightly divergent margins located parallel to longitudinal indistinct ridge (Fig. 4A-C). Dorsal surface of fore tibia with few scattered, short, stout setae of same kind, solitary hair-like setae, and hair-like setae in bunches (consisting of 2-4 setae), oblique regular row of long, stout, hair-like setae. Outer and inner margins of tibia with relatively short hair-like setae; inner margin with several elongate, pointed, stout setae.

Middle and hind femora (Fig. 4B, C), in contrast to fore femur, more slender, ca 2.6-2.7 times longer than wide, with denser submarginal row of stout setae, inner margin with regular row of long, stout, hair-like setae. Outer margins of middle and hind femora and tibiae with a regular row of long, stout, hair-like setae (Fig. 4D, G). Setation of dorsal surface of middle and hind tibiae most similar to those of fore leg, but oblique regular row of long, stout setae longer, and reaching distal end of tibia (Fig. 4G).

Tarsal claws moderately hooked, lacking subapical denticles, with 4-6 medial denticles and several (3-5) subapical setae (Fig. 4E, F).

Abdomen. All terga with moderately developed, narrowed (especially on terga V-X) median tubercles (Fig. 5A, F); the largest on terga V-VIII; tubercle of tergum X narrow and pointed. Median tubercles of terga I-IX distinctly elongate in lateral view (Fig. 5C). Median tubercles covered with short stout setae with divergent margins (Fig. 5E). Posterolateral projections moderately developed on segments VI-IX, and slightly marked on segments II-V (Fig. 5B).

Posterior margin of terga I-V with row of long, stout, hair-like setae; posterior margin of terga VI-IX with row of elongate (on tergum VI) and short (all other terga) stout setae with rounded apices (Fig. 5D); posterior margin of tergum X without stout setae (Fig. 5F). Mainly median area of terga with scattered short stout setae with divergent margins; most numerous on segments VI-X (Fig. 5G, H). Lateral areas of dorsal surfaces of terga III-VI with thin, hair-like setae and long, stout setae with serrated margins and apices. Narrow teeth present on posterior margin of submedian area of terga III-IV; the same teeth present on median and lateral areas of posterior margin of terga V-VI (they are not numerous at lateral areas) (Fig. 5D) and across entire posterior margin of terga VII-X (on tergum X not numerous); this kind of teeth absent on posterior margin of terga I-II. Sterna surface with a few scattered hair-like setae (Fig. 5B).

Gills on segments II-V (Fig. 6A, E-H); gill II with dorsal lamella operculate, oval and with entire margin, mainly basal half covered with scattered short stout setae (Fig. 6B); gills III-V with dorsal lamella incised medially.

Cerci length subequal to the body length, posterior margins of central segments with hair-like and forked stout setae; length of the stout setae less than length of corresponding segment (Fig. 5I). Paracercus absent.

Subimagos. Wings wholly grey, semitransparent in subimagos of both sexes.

Male imago. Body length: 5.6-6.5 mm; forewing length: 5.6-5.9 mm; cerci length: 11.0-13.3. General coloration brown; thorax dark brown. Turbinate eyes brick-colored (Fig. 7A, E).

Fore leg (Fig. 7E): coxa, trochanter, and femur brown; tibia whitish, its basal and distal ends distinctly marked with black; tarsus segment I blackish; tarsi segments II-V whitish, with slightly blackish distal ends; tarsal claws blackish. Middle and hind legs (Fig. 7A): coxa brown, all other parts yellowish; femora with narrow, intermittent longitudinal black line along outer margin; dorsal surface with several longitudinal indistinct smudges; lower protuberance of knee brown; distal end of tibia blackish. Both claws on fore leg blunt; inner claw at middle and hind legs hooked and pointed and outer claw blunt.

Main area of fore wing transparent (Figs 7A, 8A); only basal area with a black marking, costal and subcostal fields translucent, milky. Pterostigmatic area with 8-10 cross-veins, several of them divided. Hind wing elongate, with large costal process. Three or four cross-veins between Sc and RA; two cross-veins between RA and IRA (Fig. 8B).

Abdominal terga IV-VIII with small pointed median tubercles, in some specimens these tubercles distances on terga IV-V only (Fig. 8C). Abdominal segments VI-IX with distinct rounded apically postero-lateral projections, largest on segments VIII and IX (Fig. 7B). Segments II-V with remnants of gill sockets (Fig. 7D). Genitalia: whitish; styliger plate straight to concave; forceps 3-segmented; segments I and II approximately same length; segment I subcylindrical; segment II slightly expanded at apex; segment III rounded apically, elongate, 1.8-1.9 times as long as wide. Penis lobes with rounded apices; lobes expanded closer to apices, maximum width on ca 0.7 of their length; fused for entire length except the apex; on ventral side a groove ends at the middle of the penis (Fig. 7B, C).

Female imago. Body length: 6.0 mm; forewing length: 5.9 mm; cerci length: 12.8 mm. General coloration brown. Legs coloration as in male imago. Turbinate eyes brown.

On fore leg outer tarsal claw hooked and pointed and inner claw blunt. On middle and hind legs outer tarsal claw blunt and inner hooked and pointed. Wings venation as in male imagos, but longitudinal veins browner. Only abdominal segments VII-IX with distinct rounded apically postero-lateral projections, largest on segments VIII and IX. Abdominal terga IV-VIII with small pointed median tubercles. Tergum X with longitudinal distinctly divergent median concavity that reach posterior margin. Segments II-V with remnants of gill sockets. Subgenital plate not elongate, with wide and shallow concavity. Subanal plate rounded.

Egg (dissected from mature larva). Shape (Fig. 6C) ovoid, with one polar cap; chorion lacking attachment structures; without geometrical marcorelief, only microgranules present. Another kind of observed eggs (Fig. 6D) we considered as unformed yet; lacking polar cap, microgranules on chorion indistinct; whole surface covered with numerous depressions and holes.

Distribution.

Himalaya (Uttarakhand, India). All Indian representatives of Dudgeodes, excluding D. selvakumari sp. nov., are known from the Western Ghats only. Dudgeodes selvakumari sp. nov., which is distributed in the lower down part of Great Himalayan mountain range, is the most northern representative of the genus and family within India. This new species and D. lugens ( Navás, 1933), which is known by single female subimago from Zhou Shan Island, in Zhejiang province, China (Sartori et al. 2008), are the most northern representatives of the family anywhere.

Habitats.

Larvae of this species were collected in a mid-sized river (6-10 m wide) in a shallow woodland valley at an altitude of about 400 m a.s.l. in the southern foothills of the Great Himalaya Range (Nainital District, Uttarakhand state, India). The river was relatively warm (24-26 °C), had a current of moderate velocity (ca 0.3-0.7 m/s), and was with a mainly stony or rocky substrate. The river is located in the recreational zone of the Jim Corbett National park with a weak anthropogenic load. Larvae were collected from the riparian zone from stones or vegetation at local current velocity 0.05-0.2 m/s (Fig. 16A-D), along with different Baetis sp. ( Baetidae), Heptageniidae, Choroterpes sp. ( Leptophlebiidae), Caenis sp. ( Caenidae), Asiagomphus sp. ( Gomphidae), Macromyia sp. ( Macromiidae), Protohermes sp. ( Corydalidae), Agapetus sp. ( Glossosomatidae), Chimarra sp. ( Philopotamidae), Marilia sp. ( Odontoceridae), and Macrobrachium sp. ( Palaemonidae).

Diagnosis.

The new species can be distinguished from other representatives of the genus by the following combination of characters. Larva: (i) dorsal part of male eyes brown; (ii) antennae length 1.15 times head width, flagellum with about 15 or more segments; (iii) labrum with transversal band of long, stout, hair-like setae; (iv) prothorax with three pairs of tubercles: SMs, SLs, and Ls; mesothorax with an MP, pair of SMMs and pair of LAs; (v) forefemur without transversal row of stout setae; (vi) outer margin of forefemur covered with a regular row of long, stout, hair-like setae, a few bunches, and single, thin, hair-like setae; (vii) submarginal row of setae of forefemur distinct, consisting of elongate and short, stout setae with slightly divided margins; (viii) tarsal claw of all legs with 4-6 medial denticles and without subapical denticles; (ix) terga I-X with moderately developed, narrowed (especially on terga V-X) median tubercles; the largest tubercles on terga V-VIII; tubercle of tergum X narrow and pointed; in lateral view, median tubercles of terga I-IX distinctly elongate; (x) posterolateral projections moderately developed on segments VI-IX, slightly marked on segments II-V. Imago male: (i) fore wing with numerous cross-veins; (ii) hind wing with 3-4 cross-veins between Sc and RA, and two cross-veins between RA and IRA; (iii) penis lobes maximum width on about 0.7 of their length; (iv) abdominal terga IV-VIII with small pointed median tubercles; in some specimens these tubercles distinct on terga IV-V only; (v) abdominal segments VI-IX with rounded apically postero-lateral projections. Egg: (i) without spines on pole opposite to polar cap; (ii) surface covered with microgranules.

The larva of D. selvakumari Martynov & Palatov, sp. nov. is easily distinguished from other Indian Dudgeodes species by: (i) absence of tubercles on head; (ii) number of tubercles on pro- and mesonotum; (iii) forefemur setation; (iv) shape of fore femur; (v) absence of subapical denticles on tarsal claws; (vi) shape of gill II; (vii) shape of median tubercles of abdominal terga.