Tricorythus furcifer, 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 : 274-279

Tricorythus furcifer sp.n.

( Figs 1–14 , 26, 27 )

Etymology. Furcifer (Lat.) , fork-bearing; refers to the large and heavily sclerotized fork-like penis of male imago.

Material examined. Holotype: L-S-I♂ {specimen [XV](3)A2014}: ZAMBIA, river West Lunga near Mwinilunga, 20.VIII.2014, coll. N. Kluge & L. Sheyko. Paratypes: the same locality, 1 L-S-I♂, 3 L-S♂, 55 I ♂, 2 L-A ♀, 22 larvae; river Mudanyama in Mwinilunga, 14–17.VIII.2014, coll. N. Kluge & L. Sheyko: 12 I ♂, 10 larvae; river Mutanda at Mutanda Falls 30 km SSW Solwezi, 10–12.VIII.2014, coll. N. Kluge & L. Sheyko: 27 I ♂.

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 Mwinilunga and 2 ♀ alates from Mutanda.

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

HYPODERMAL COLORATION ( Figs 1–4 ): Head and thorax dorsally light ocher with dark gray maculae, thorax ventrally light ocher. Legs ocher; anterior side of each femur with four dark gray longitudinal stripes—stripe on outer margin, stripe on inner margin and two stripes connected distally, or with fragments of these stripes, or stripes fused together ( Fig. 4 ); posterior side of femur with longitudinal stripe ( Fig. 2 ). Protoptera in male and female ocher with dark gray stripes corresponding to convex veins. 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 5) 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 8–12 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 1–4 ; as in Kluge 2010: Figs 12 ). Femora moderately wide ( Figs 1–5 ). 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. 5 ; as in Kluge 2010: Figs 7–9 ). Anterior surface of middle and hind femora with irregularly arranges stout spatulate setae nearly as large as spatulate setae on outer margin ( Fig. 5 ). 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 hind leg, besides it, with dense regular longitudinal row of spatulate setae on outer-posterior side (as in Kluge 2010: Fig. 9 ). On tibia of middle leg, outer-posterior side either without stout setae, or with one or two occasional long stout setae ( Fig. 5 ). 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 at most elongate and blunt. Vestiges of tergalii VII absent.

Larval protopenis large, with paired lobes widely divergent, nearly reaching margins of genital plate ( Fig. 7 ). When subimaginal/imaginal penis is developed under larval cuticle, proximal part of its unpaired stem is developed in inverted and retracted condition ( Figs 7 , 10 ). Before molt to subimago, penis has both new cuticles completely developed, subimaginal cuticle being very thin, elastic and colorless, and imaginal cuticle being thick and completely pigmented ( Fig. 10 ).

Subimago, male. CUTICULAR COLORATION AND TEXTURE: Cuticle of pronotum brown with blanks of composite branched shape; densely covered with microtrichiae except for blanks. Cuticle of pterothorax with sclerites brown and membranes colorless. Mesonotum brown, with antelateroparapsidal suture and anterolateral scutal costa darker, lateroscutum and posterior scutal protuberance lighter ( Fig. 9 ). 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. 9 ). Cuticle of all legs partly colorless, with contrasting brown longitudinal stripes ( Fig. 11 ). Cuticle of abdominal terga and sterna brown, with colorless median stripe on terga and small paired blanks; styliger with large roundish blank at middle; gonostyli light, with contrasting brown band at joining of first and second segments ( Fig. 12 ). Cuticle of caudalii colorless.

HYPODERMAL COLORATION: As in imago.

GENITAL STRUCTURE. Styliger and gonostyli as in Fig.12 . Penis much shorter than in imago, because its stem retains the same inverted condition as in larva (as in Fig. 10 ).

Imago, male. HYPODERMAL AND CUTICULAR COLORATION: Head and thorax light ocher with dark gray or brown hypodermal maculae; cuticular pigmentation poorly developed. Wings tinged either with light gray, or with light brown, especially intensively in costal and subcostal fields. 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. Abdominal terga and sterna nearly entirely tinged with gray or brown hypodermal coloration. Styliger tinged with the same color ( Fig. 13 ). Gonostyli pale ocher, cuticle with light brownish band at apex of first segment ( Fig. 13 ). Penis with cuticle proximally colorless, distally intensively colored by ocherbrown; hypodermal coloration absent ( Fig. 13 ). Caudalii with contrastingly alternating dark gray and lighter portions.

SHAPE: Eyes small, as in female (as in Kluge 2010: Fig. 28 ). Mesonotum with lateroparapsidal suture strongly curved ( Fig. 9 ). Genitals as in Figs 6, 8 , 13 . Styliger projected forming prominent lobe with median incision; its margin densely covered with globular papillae (of the same shape as papillae on median side of second segment of gonostylus) ( Fig. 14 ). Penis unusually long, much longer than gonostyli, well-sclerotized; narrowed between unpaired proximal part and bifurcate distal part; arms of distal part large, divergent, pointed and heavily sclerotized.

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 ( Figs 26, 27 ). Chorion with a net-like relief with large cells. Two polar caps, one divided to central part and collar, another smaller and simple.

Dimension. Wing length (and approximate body length) of male 5.5 mm, of female 6 mm.

Comparison. Male imago, subimago and mature larva of T. furcifer sp.n. differ from all other species of Tricorythus by widely divergent and sharply pointed apical branches of penis. Following features of genital structure are common for T. furcifer sp.n. and T. tinctus Kimmins 1956 : unpaired stem of penis is very long in imago, being in subimago and mature larva proximally inverted and retracted, so that larval protopenis is rather short ( Figs 6–8 , 10, 13 ; Kluge 2010: Figs 44–49). In contrast to T. tinctus , larva of T. furcifer sp.n. has mandibular incisors not tusk-like, base of left prostheca with 3 setae, clypeus without incisions, pronotum without projected angles, stout setae on femora spatulate and blunt. Larva of T. furcifer sp.n. differs from most other species by absence of regular row of stout spatulate setae on posterior-out side of middle tibia ( Table 1 ). Eggs of T. furcifer sp.n. differ from eggs of other species by presence of two polar caps.

Peculiar characters are marked by bold. Reference to figures are shortly given in square brackets as following: [2010:86] means (Kluge 2010: Fig. 86).

Figures

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).

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

Tables

TABLE 1. Diagnostic larval characters of described species of African Tricorythus.

T. varicauda	T. tener sp.n.	T. furcifer	T. discolor	T. exophthalmus T. tinctus
		sp.n.
Eyes of ♂ small	small	small	large	large small
[2010:86]	[Fig.17]	[Fig.1]		[2010:88] [2010:87]
Clypeus simple	simple	simple	simple	simple with
[2010:12]				incisions
				[2010:37]
Mandibles simple	simple	simple	simple	simple tusk-like
[2010:4-6]				[2010:38]
Setae at base of 3	3 (3–4)	3 (3–5)	numerous	numerous numerous
left prostheca [2010:5]				[2010:58] [2010:38]
Pronotum simple	simple	simple	with sexual	with sexual with
[2010:12]			dimorphism	dimorphism projected [2010:52-54] angles [2010:35]
Hypodermal dark	♂ light,	light, veins	dark	dark dark or bicolor
color of [2010:88]	costal margin dark;	dark		[2010:88] [2010:87]
protopteron	♀ dark [Fig.17–19]	[Fig.1–4]
Setae on anterior short side of mid and [2010:8-9]	short [Fig.23]	long [Fig.5]	short	absent short [2010:62-63] [2010:40-41]
hind femur
Outer-posterior present	present	absent	absent	present present
row of setae on [2010:8]	[Fig.23]	[Fig.5]		[2010:62]
mid tibia
Protopenis long	short	bifurcate	short	short short
[2010:20]	[Fig.25]	[Fig.7]		[2010:69] [2010:49]
Developing simple	simple	telescopic	simple	simple telescopic
imaginal penis [2010:21]	[Fig.25]	[Fig.7]		[2010:49]