Clypeocaenis malzacheri Srinivasan, Sivaruban, Barathy & Isack, 2022

Srinivasan, Pandiarajan, Sivaruban, T., Barathy, S., Isack, Rajasekaran & Jacobus, Luke M., 2022, A new species of Clypeocaenis Soldán 1978 (Ephemeroptera: Caenidae) from Tamil Nadu, India, Zootaxa 5091 (3), pp. 467-476 : 468-472

publication ID	https://doi.org/ 10.11646/zootaxa.5091.3.6
publication LSID	lsid:zoobank.org:pub:B90FAB24-9181-4E89-AADE-9094B7B84740
DOI	https://doi.org/10.5281/zenodo.5848347
persistent identifier	https://treatment.plazi.org/id/994B87B8-FC3B-495F-FF2D-3EA7C6BCFDC3
treatment provided by	Plazi
scientific name	Clypeocaenis malzacheri Srinivasan, Sivaruban, Barathy & Isack
status	sp. nov.

Treatment

Clypeocaenis malzacheri Srinivasan, Sivaruban, Barathy & Isack sp. nov.

( Figs. 1–8 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 )

Materials Examined. Holotype (in ethanol): Male larva (Reg. No. ZSI–SRC/I/E/599), South India, Tamil Nadu, Theni district , Kurangani , Kottakudi River , 10°08′09″N, 77°25′52″E; 632 m; 28.x.2020, Pandiarajan Srinivasan & Rajasekaran Isack GoogleMaps . Paratypes (also in ethanol): 1 male larva (Reg. No. ZSI–SRC/I/E/600), 2 male larvae ( AMC / ZN/192), 4 female larvae ( AMC /ZN/193), same data as holotype GoogleMaps .

Descriptions.

Final larval instar. Body length (without cerci): 2.5–2.7 mm (male) and 2.9–3.1 mm (female); cerci lengths about 1.15 mm; antennae lengths 0.81–0.85 mm. General body coloration usually dark brown dorsally and pale yellow ventrally, though sometimes lighter dorsally. Head: General color brownish, with vertex darker with branch-like pigmentation ( Fig. 1 View FIGURE 1 ); epicranial sutures dark. Compound eyes black, ocelli whitish. Scape and pedicel chagrined without any setae; pedicel length 1.6 times length of scape. Frons distinctly protruded to proximal margin of second flagellum segment ( Fig. 2A View FIGURE 2 ), with two simple setae on anterior margin with lengths about ¼ length of antenna. Labrum ( Fig. 2B View FIGURE 2 ) 2.3 times as broad as long; emargination without any setae; anterior margin with row of long and thin setae; dorsum with few, long and thin setae near anterior margin and lateral margin. Mandibles ( Fig. 2C View FIGURE 2 ) with three denticles on outer incisor and two transversely arranged denticles on kinetodontium; basal area below mola chagrined and with no setae; two transverse row of simple setae on the dorso-lateral surface in which apical row bears 4 simple setae and basal row with numerous long, simple setae; basal half of mandible chagrined. Maxilla ( Fig. 2D View FIGURE 2 ) with two-segmented palp with protuberance; segment II 3.1 times longer than segment I; distal 3/4 of segment II covered with long, thin setae; outer margin of segment I with row of 8 stout setae (n=4) and inner margin bare. Galea-lacinia with row of 5 long, thin setae in the inner margin. Apical margin of superlingua covered with long, simple setae; hypopharynx with very short spines at apical margin. Labium ( Fig. 2E View FIGURE 2 ): glossae ovate with apical margins covered with thin setae; paraglossae bent towards glossae and bluntly pointed, covered with thin setae; palps three-segmented, with segment III longer than segments I and II, segment III with bluntly pointed tip ( Fig. 2F View FIGURE 2 ), segment III with two transverse rows of five stout setae at distal margin, segment II with two bipinnate bristles at distal margin ( Fig. 2G View FIGURE 2 ), and segment I with seven unipinnate bristles on outer margin ( Fig. 2H View FIGURE 2 ). Thorax: Pronotum dark brownish, margins light brownish. Anterolateral areas of pronotum produced. Mesonotum dark brownish. Legs: Evenly covered with scales, coloration pale to medium brown; ovoidal cuticular blank located on the proximal half of ventral surface of each femur of all legs ( Fig. 4A View FIGURE 4 ). Foreleg ( Fig. 3A View FIGURE 3 ): lengths of femur/ tibia/ tarsus/ claw viz., 0.50/ 0.47/ 0.49/ 0.15 mm. Coxa denticulate with thin setae on inner and outer margins. Femur ( Fig. 4B View FIGURE 4 ) with scattered spine-like setae along inner margin; outer margin with long, simple setae present on part of proximal half and row of spatulate setae present on part of distal half; dorsal surface with 3 or 4 stout setae ( Fig. 4B & 4C View FIGURE 4 ). Tibia with two transverse rows of very long filtering setae on dorsal side, prolonged on ventral side in longitudinal direction ( Fig. 4B View FIGURE 4 ). Tarsus with loose row of 6 long, simple setae extending nearly longitudinally; outer margin with scattered hair-like setae; 8–10 long, bipinnate setae on inner margin. Claw long and slender, with 4 denticles varying in size, basal denticle very small compared to others ( Fig. 4D View FIGURE 4 ). Midleg ( Fig. 3B View FIGURE 3 ): lengths of femur/ tibia/ tarsus/ claw viz., 0.53/ 0.35/ 0.31/ 0.13 mm. Coxa similar to foreleg. Femur ( Fig. 5A View FIGURE 5 ) with rows of spatulate setae on outer and inner margins and two feathery setae near surface of distal half of outer margin. Tibia ( Fig. 5B View FIGURE 5 ) inner margin with row of spines on the distal half and one large, monopectinate seta present; outer margin with scattered hair-like setae. Tarsus ( Fig. 5B View FIGURE 5 ) inner margins with row of spine-like setae; outer margins with scattered hair-like setae; 4 bipinnate bristles present medially ( Fig. 5C View FIGURE 5 ). Claw long and hooked with 3 denticles increasing in size distally ( Fig. 5D View FIGURE 5 ). Hindleg ( Fig. 3C View FIGURE 3 ): lengths of femur/ tibia/ tarsus/ claw viz., 0.73/ 0.48/ 0.38/ 0.17 mm. Coxa similar to foreleg. Femur ( Fig. 5E View FIGURE 5 ) with row of feathered setae on outer margin and row of broadly spatulate and pinnate bristles on inner margin ( Fig. 5F View FIGURE 5 ); outer margin with 2 simple setae in distal half ( Fig. 5G View FIGURE 5 ). Tibia with row of spatulate setae on outer margin and row of simple setae with broad apices on inner margin. Tarsus and claw similar to midleg. A bdomen: Terga I, VIII, and IX brown; others whitish and laterally translucent. Tergum II ( Fig. 6A View FIGURE 6 ) with upright, backwardly curved blunt medial projection; posterior margin with pointed spines; surface with scales. Terga VII and VIII with medial protuberances ( Fig. 6C View FIGURE 6 ); posterior margin of tergum VII ( Fig. 6C View FIGURE 6 ) with short, bifid setae medially and pinnate setae laterally; terga VIII –X with denticles on posterior margins. Sterna VII – IX light brown; others whitish; hind margin of sternum IX slightly concave and denticulate ( Fig. 6B View FIGURE 6 ). Tergalii: tergalius I bluntly pointed, two-segmented; segment II three times as long as segment I. Tergalius II quadrate ( Fig. 6D View FIGURE 6 , 7A View FIGURE 7 ), pale brown, evenly covered with scales ( Fig. 6D View FIGURE 6 ); posterior margin with stout, multi-branched bristles; inner margin with row of small, simple setae; outer margin with stout, multi-branched bristles. Tergalii III– VI subtriangular ( Fig. 7B View FIGURE 7 ), fringed with some bifid fimbriae. Tergalii III– VI with 45–50 filaments (only 13 filaments with 2 branches, all other filaments simple). Cerci translucent.

Egg. Length: 115–120 μm; width: 60–65 μm. Elongate, about twice as long as wide ( Fig. 8A View FIGURE 8 ); chorion smooth without any epithema ( Fig. 8B View FIGURE 8 ); micropyle of moderate length; mouth not broadened with circular sperm-guide ( Fig. 8C View FIGURE 8 ).

Imago. Unknown.

Larval Diagnosis. The new species has a unique combination of features: (i) frons strongly protruding up to the proximal margin of the second flagellum segment ( Fig. 2A View FIGURE 2 ); ii) ovoidal cuticular blank located on the proximal half of ventral surface of each femur of all legs ( Fig. 4A View FIGURE 4 ); iii) forefemora lack long setae in the middle of the inner margin ( Fig. 4B View FIGURE 4 ); iv) claws with 4 denticles in the foreleg varying in size, basal denticle very small compared to others and, 3 denticles increasing in size distally in the mid and hindleg ( Fig. 4D View FIGURE 4 & 5D View FIGURE 5 ); v) abdominal tergum II with upright, backwardly curved blunt medial projection ( Fig. 6A View FIGURE 6 ); and vi) hind margin of abdominal sternum IX slightly concave and denticulate ( Fig. 6B View FIGURE 6 ).

Etymology. This species is named after Dr. Peter Malzacher (Ludwigsburg, Germany), in honor of his dedication to caenid mayflies. The epithet “malzacheri” is used as a nomen in the genitive case.

Distribution. Kurangani hills, Tamil Nadu, India.

Biology. The larvae of Clypeocaenis malzacheri sp. nov. show a significant level of languor in their activity. They live on cobble and pebbles in areas with slow current. They were found in water with temperature ranging between 21°C–23°C and pH ranging between 7.1–7.3.