Tricorythis tener, Kluge, Nikita J., 2016

Kluge, Nikita J., 2016, Two new species of Tricorythus Eaton 1868 (Ephemeroptera, Tricorythidae) from Zambia, Zootaxa 4092 (2), pp. 273-285 : 279-282

Tricorythis tener sp.n.

( Figs 15–25 , 28, 29 )

Etymology. Tener (Lat.) , delicate.

Material examined. Holotype: L-S-I♂ {specimen [VI](18)2014}: ZAMBIA, river Luangwa near Luangwa Bridge, 8.VIII.2014, coll. N. Kluge & L. Sheyko. Paratypes: the same locality, 2–7.VIII.2014: 2 L-S-I♂, 2 L-S♂, 4 L-A♀, 30 larvae; river Mutanda at Mutanda Falls 30 km SSW Solwezi, 10–12.VIII.2014, coll. N. Kluge & L. Sheyko: 2 I ♂; river West Lunga near Mwinilunga, 14–20.VIII.2014, coll. N. Kluge & L. Sheyko: 1 L-S♂, 3 I ♂; river Zambezi above Victoria Falls, 25–31.VIII.2014, coll. N. Kluge & L. Sheyko: 73 I ♂, 10 A♀, 5 larvae.

Additional material: alate females without eggs, collected at light in localities where both T. furcifer sp.n. and T. tener sp.n. were collected, so systematic position of these females is unclear; these are 73 ♀ alates from river West Lunga and 2 ♀ alates from river Mutanda.

Descriptions. Larva. CUTICULAR COLORATION: Cuticle entirely ocher, nearly unicolor, without maculation.

HYPODERMAL COLORATION (Figs 17–19): Head and thorax dorsally light ocher with dark gray maculae, thorax ventrally light ocher. Legs light ocher; anterior side of each femur with four dark gray longitudinal stripesstripe on outer margin, stripe on inner margin and two stripes connected distally (Fig. 18), or with fragments of these stripes (Fig. 17). Protoptera different in male and female: in male light ocher or whitish with costal and subcostal fields darker gray (Fig. 17), in female entirely darkened with gray (Figs 18, 19). Abdominal terga from light ocher to dark gray, sterna lighter. Tergalii with dorsal lamellate lobe gray with margins colorless, ventral lobe gray. Caudalii either unicolor light, or with dark maculae in proximal part.

SHAPE AND SETATION: Frons and clypeus lacking projections (as in Kluge 2010: Fig. 12 ). Eyes of male as small as in female. Mandibles with incisors not elongated, curved (as in Kluge 2010: Figs 4–6 ); left prostheca asymmetrically or symmetrically widened apically, with 3 (occasionally 4) bristle-like processes at base (as in Kluge 2010: Fig. 5 ); shape of right prostheca usual for Tricorygnatha (as in Kluge 2010: Fig. 6 ). In last larval instar, transverse row on ventral side of maxilla consists of 9 (occasionally 10 or 11) bristles. Maxilla with long palp.

Pronotum moderately wide; anterolateral angles rounded and only slightly projected forward; anterior margin between them in both sexes nearly straight; mesonotum not shortened (Figs 17–19; as in Kluge 2010: Figs 12 ). Femora moderately wide (Figs17–19; 23). Stout setae on femora (which form rows characteristic for Pantricorythi) elongate and spatulate (i.e., apically widened and blunt), irregularly arranged: on fore femur they form irregular transverse row, not continuous on outer margin, on middle and hind femora they form longitudinal row on outer margin ( Fig. 23 ; as in Kluge 2010: Figs 7–9 ). Anterior surface of middle and hind femora with irregularly arranges stout spatulate setae much smaller than spatulate setae on outer margin ( Fig. 23 ). Tibia of each leg with three longitudinal rows of stout setae: on inner-anterior side, on inner side and on inner-posterior side; tibia of middle and hind leg, besides it, with dense regular longitudinal row of spatulate setae on outer-posterior side ( Fig. 23 ). Fore tarsus in male larva not widened, the same as in female larva.

Abdominal terga with tergalial cavities not bordered by long setae. Denticles on hind margins of abdominal terga irregular, weak, elongate, either pointed, or blunt, or terminated by several points. Vestiges of tergalii VII absent. Protopenis not large, far not reaching posterior margin of genital plate, cleft up to middle, with paired lobed pressed together ( Fig. 25 ).

Subimago, male. CUTICULAR COLORATION AND TEXTURE: Cuticle of pronotum light brown with blanks of composite branched shape; densely covered with microtrichiae except for blanks. Cuticle of pterothorax with sclerites light brown and membranes colorless. Mesonotum with antelateroparapsidal suture and anterolateral scutal costa dark brown; anteronotal protuberance, medioscutum and submedioscutum light brownish; sublateroscutum a little darker; most part of lateroscutum and posterior scutal protuberance nearly colorless (Fig. 20). Microtrichiae densely cover all areas of mesonotum except for posterior scutal protuberances; posterior scutal protuberances without microtrichiae, with net-like relief. Basal plate of wing has distinctly outlined subimaginal sclerite of characteristic shape and brown color (Fig. 20). Cuticle of fore leg partly colorless, with contrasting brown longitudinal stripes (Fig. 21). Cuticle of middle and hind legs either as on fore leg, or entirely colorless. Cuticle of abdominal terga and sterna light brown, with colorless median stripe on terga and small, contrasting, paired blanks; sternum IX has a T-shape blank on anterior margin and midline; gonostyli entirely light (Fig. 22). Cuticle of caudalii colorless.

HYPODERMAL COLORATION: As in imago.

Imago, male. HYPODERMAL AND CUTICULAR COLORATION: Head and thorax light ocher with dark gray hypodermal maculae; cuticular pigmentation poorly developed. Wings colorless, with proximal parts of costal and subcostal fields tinged with gray. Legs partly colorless, partly with contrasting dark brown hypodermal coloration: femur with longitudinal stripes or/and apical band; tibia with or without dark middle part. Abdomen light ocher, terga tinged with light gray except lateral areas corresponding to larval tergalial cavities. Abdominal sterna, styliger, gonostyli and penis entirely lacking hypodermal and cuticular pigmentation. Caudalii pale ocher with contrasting dark gray proximal half of each segment.

SHAPE: Eyes small, as in female (as in Kluge 2010: Fig. 28 ). Mesonotum with lateroparapsidal suture strongly curved (Fig. 20). Genitals as in Figs 15, 16 , 24 : Styliger short, with posterior margin either nearly straight ( Fig. 16 ), or shallowly concave ( Figs 15 , 24 ) or shallowly convex. Papillae on posterior margin of styliger narrow and sparse. Penis non-sclerotized, narrow, nearly parallel-sided, bifurcates very close to apex, with apices brought together ( Fig. 24 ).

Alate female. One alate stage, without molt from subimago to imago (as in other Tricorygnatha). Texture of mesonotum as in male subimago: posterior scutal protuberances without microtrichiae, with net-like relief.

Egg. Chorion with characteristic relief ( Figs 28, 29 ). One polar cap, divided to central part and collar.

Dimension. Wing length (and approximate body length) of male 4.5 mm, of female 6 mm.

Comparison. Male imago and subimago of T. tener sp.n. differ from most other species by narrow penis with distal paired lobes very short and pressed together. Among African species of Tricorythus , similar shape of penis is present in T. discolor (Burmeister 1839) , from which T. tener sp.n. differs by small eyes of male. Larva of T. tener sp.n. is very similar to larva of T. varicauda (Pictet 1843) , differs by short protopenis of male ( Table 1 ).

Figures

FIGURES 9 – 16. 9 – 14, Tricorythus furcifer sp. n.: 9, left half of exuviae of subimaginal mesonotum; 10, subimaginal and imaginal penis with gonoducts and left gonad, extracted from mature larva; 11, exuviae of subimaginal fore leg; 12, exuviae of subimaginal abdomen; 13, imaginal genitals (holotype); 14, the same, enlarged fragment (arrows show globular papillae); 15, Tricorythus tener sp. n., imaginal genitals (holotype); 16, the same, paratype.

FIGURES 23 – 25. Tricorythus tener sp. n. 23, middle leg of larva, anterior view; 24, genitals of male imago, ventral view; 25, apex of ninths sternum and protopenis of mature male larva with developing subimaginal and imaginal genitals inside, dorsal view (hidden parts of subimaginal and imaginal cuticle shown by interrupted and dotted lines; gonads and gonoducts shown by dotted lines) (23, 24, holotype).

FIGURES 26 – 29. Eggs. 26, 27, Tricorythus furcifer sp. n.; 28, 29 Tricorythus tener sp. n.

FIGURES 1 – 4. Tricorythus furcifer sp. n., last instar larvae: 1, male larva, dorsal view; 2, the same, ventral view; 3, 4, female larvae.

FIGURES 5 – 8. Tricorythus furcifer sp. n. 5, middle leg of larva, anterior view (holotype); 6, genitals of male imago, lateral view; 7, ninths sternum and protopenis of mature male larva with developing subimaginal and imaginal genitals inside, dorsal view (hidden parts of subimaginal and imaginal cuticle shown by interrupted and dotted lines; gonads and gonoducts shown by dotted lines); 8, genital of male imago, dorsal view (gonoducts shown by dotted lines).