Monocentroptilum badium (Kopelke 1980) Kluge, 2018

Kluge, Nikita J., 2018, A new Afrotropical genus Monocentroptilum gen. n. (Ephemeroptera: Baetidae: Protopatellata), Zootaxa 4486 (2), pp. 115-128 : 120-125

Monocentroptilum badium (Kopelke 1980) comb. n.

( Figs 1–58 )

Centroptilum badium Kopelke 1980a: 113 (♂ and ♀ imago); Kopelke 1980b: 301 (eggs).

Afroptilum (Afroptilum) badium: Gillies 1990a: 99 .

Crassabwa badia : LugO-OrtiZ & McCafferty 1996b: 238.

Material examined. UGANDA, Kanungu district, river Munyaga just downstream Bwindi National Park, 0º58'40"S, 29º37'15"E, 23–26.VII.2007, coll. N. Kluge: 3 L-S-I ♂, 1 S-I ♂, 1 L-S/I ♂, 2 L-S ♂, 6 L-S-I ♀, 5 L-S ♀, 59 larvae; river Ishasha downstream Bwindi National Park, 0º51'S, 29º39'30"E, 14.VII.2007, coll. N. Kluge: 3 larvae; Kasese district, Rwenzory mountains, tributary of river Mubuku upstream Ruboni, 0º21'N, 30º02'E, 28.VII– 6.VIII.2007, coll. N. Kluge: 1 larva.

Descriptions. Larva. CUTICULAR COLORATION. Nearly unicolor brown ( Fig. 1 ): head brown; pronotum and mesonotum brown with diffusive lighter areas ( Fig. 2 ); thoracic pleura brown, with lighter membranes; legs unicolor brown; abdomen with terga unicolor brown, sterna unicolor light brownish (even sigilla on terga and sterna have the same color as background) ( Fig. 3 ); cerci and paracercus unicolor brown.

HYPODERMAL COLORATION. In both sexes abdominal terga with intensive brown coloration as in winged stages ( Fig. 4 ).

STRUCTURE. General appearance, including shape of head, thorax, legs, abdomen and caudalii ( Fig. 1 ) similar to that of Baetis s.str.

Frons not narrowed, frontal suture obtuse-angled ( Fig. 27 ). Labrum roundish; dorsal surface with pair of submedian setae, pair of smaller setae by sides of them and 3 pairs of antero-lateral setae, not forming a row ( Fig. 5 ). Mandibles elongated perpendicular to axis of rotation ( Figs 8–9 ); on each mandible incisor fused with kinetodontium at most length; each incisor with 4 denticles, apical denticle longest; left prostheca with 3 blunt denticles and 2–3 pointed denticles; right prostheca pointed, adjacent to kinetodontium, with few slender processes (not visible on Fig. 9 ); setae between prostheca and mola on right mandible dense, on left mandible few or absent. Maxilla ( Fig. 6 ) of the « Baetis - type », i.e. 1 st dentiseta massive, canine-like and bent toward canines; maxillary palp 2-segmented. Labium ( Fig. 7 ): paraglossae wider and slightly longer than glossae; latero-apical setae of paraglossa form 3 rows on its distal part; ventro-median setal row consists of 2 o 3 setae forming oblique row; dorso-median setal row reduced to 2 setae located close to apex. Labial palp with 2nd segment long, apically widened and projected medially, 3rd segment small ( Fig. 7 ).

Pronotum with lateral margins rounded ( Fig. 23 ). Mesonotum with 2 pairs of small protuberances: one pair near posterior margin between protoptera, another in front of them ( Figs 1 , 23 , 28 ). Dorsal side of head, pronotum and mesonotum with minute triangular setae, each narrow at base and sharply widened apically ( Fig. 24 , 28 ); elongated setae of the same type form dense bunches on top of each protuberance of mesonotum ( Figs 25 , 28 ).

Leg setation as following ( Figs 18, 20–21 ): Outer margin of femur in proximal half with one row of long stout blunt setae; in distal half with 4 such setae arranged it 2 pairs ( Figs 18, 20 ). Patella-tibial suture absent on fore leg ( Fig. 18 ), present on middle and hind legs ( Fig. 20 ). Outer margin of tibia apically with one stout clavate seta. Inner margin of tibia with small sparse stout setae; apex of tibia with 3–5 larger unequal pointed stout setae ( Fig. 21 ); apex of patella with 1–2 such setae (on fore leg, where patella-tibial suture is absent, these enlarged seta either present or not). Inner margin of tarsus with row of pointed stout setae progressively increased from most proximal to most distal one.

Claw asymmetric, with pair of proximal denticles, with 4–5 denticles of anterior row (posterior row of denticles absent), with symmetric pair of subapical setae ( Figs 19, 22 ).

Metanotum and abdominal terga with short rounded scales in semicircular sockets; their sockets lack operculae ( Fig. 30 ). Posterior margin of metanotum smooth, without denticles. Denticles on posterior margins of abdominal terga I–IX short, wide, blunt, nearly semicircular, membranous, colorless, form regular row ( Fig. 30 ); on all terga, including tergum IX, this row not interrupted medially. On abdominal tergum X, projected median part without denticles on posterior margin; side parts with irregular pointed denticles. Sterna of posterior half of abdomen with scales in semicircular sockets, like that on terga. Posterior margins of abdominal sterna I–VII smooth; posterior margins of sterna VIII–IX and paraprocts with pointed sclerotized denticles ( Figs 31 , 44 ).

All tergalii I–VII obliquely truncate in such a manner that costal margin seems shorter than anal margin; both costal and anal margins sclerotized ( Figs 1, 3 , 10–16 ); in distal part sclerotized and non-sclerotized margins with few seta-bearing denticles ( Fig. 17 ); tergalial tracheae invisible (very narrow, short and colorless); tergalius I narrow, tergalii III–VII progressively decrease in size.

Cerci and paracercus with well-developed primary swimming setae; segments of cerci with boundaries slightly inclined; denticles on their posterior margins triangular, slightly enlarged toward lateral side of cercus; secondary swimming setae absent ( Fig. 29 ). Paracercus shorter than cerci ( Fig. 1 ).

RESPIRATORY MOVEMENTS. Absent; tergalii unable to make rhythmical movements; being placed to stagnant water, larva cannot live for a long time.

Subimago. CUTICULAR COLORATION. Pronotum brown; mesonotum brown with contrasting colorless medioparapsidal suture; thoracic pleura and sterna partly brown, partly colorless ( Fig. 32 ). Shape of postsubalar sclerite as seen in Fig. 43 . Wings brown due to brown rings around base of each microtrichion (as in Kluge 2012b: Fig. 22 ). Legs with brown markings on femur and base of tibia ( Figs 37–39 ). Abdomen nearly unicolor brown; each tergum with pair of slightly darker brown triangular markings; in male sternum IX and gonostyli lighter than other sterna and terga. Cerci colorless.

TEXTURE. On all legs of male and female all tarsomeres covered by pointed microlepides ( Fig. 39 ).

Imago, male. Described by Kopelke (1980a).

COLORATION ( Figs 32–34 ). Head brown. Turbinate eyes with facetted surface and proximal ¼ of stem orange, other part of stem yellow. Thorax with sclerites uniformly brown, membranes ocher. Wings colorless, veins light. Fore leg with femur brown, tibia and tarsus lighter brown. Middle and hind legs pale ocher, coxa and base of femur tinged with brown. All abdominal terga brown (both hypodermal and cuticular colorations), with medioanterior and medioposterior sigilla lighter; all abdominal sterna lighter brownish, also with medioanterior and medioposterior sigilla lighter ( Fig. 34 ). Genitals brown ( Figs 48–52 ). Cerci pale ocher, unicolor.

STRUCTURE. Turban eyes narrow and cylindrical ( Figs 32–33 , 42 ). Anteronotal protuberance pointed in lateral view ( Figs 32 , 42 ). Hind wing of the « Centroptilum - type »: narrow, with 2 longitudinal veins, with single hooked costal projection ( Fig. 41 ). On middle and hind leg tarsus less than ½ of tibia length, with apical spine on 1 st and 2nd tarsomeres (initial 2nd and 3rd tarsomeres) (as in Fig. 39 ).

Male genitals ( Figs 44–52 ): Unistyligers with ventral surface sclerotized and pigmented except proximalmedian angle ( Figs 46 , 49 ); median styligeral sclerite present, elongate ( Figs 46 , 49, 51 ). Median styligeral muscle wide, attached to median styligeral sclerite and to unistyligers ( Figs 46 , 51 ). 1 st segment of gonostylus short and thick, with inner margin irregularly crumpled ( Figs 46 , 49, 50, 52 ). 3rd (distal) segment elongate ( Figs 46 , 48, 52 ). Gonovectes pointed, with apices sharply bent caudally and split at place of gonoduct attachment ( Figs 46 , 48, 50 ). Median part of penial bridge concave ( Figs 46 , 50 ).

Imago, female. Described by Kopelke (1980a). Coloration as in male ( Figs 35–36 ). Eyes widely separated ( Fig. 35 ). Fore tarsus with apical spine on 2nd and 3rd tarsomeres. Patella-tibial suture absent on fore leg ( Fig. 37 ), present on middle and hind legs ( Fig. 38 ).

Eggs. Oval, 0.11 mm length. Chorion with poorly expressed net-like relief with small cells ( Figs 53–58 ).

Dimensions. Fore wing length (and body length) 3.5–4.5 mm.

Distribution. Congo and Uganda.

Collecting place. Most part of larvae were collected in the river Munyaga 4 km upstream of the place where this river is served as the state boundary between Uganda and Democratic Republic of the Congo. Upstream of the collecting place, this small river runs in a dark forest of the Bwindi National Park; at this area its water is cold, mayflies are abundant, but their species diversity is limited, with domination of Tricorythus exophthalmus Kluge 2010 . Just downstream from the forest, this river runs by opened space in the village; here mayfly fauna has maximum species diversity and includes M. badium . Downstream from this place Munyaga continues to run by opened space among fields, its water becomes warmer, and mayfly fauna is poor.

Figures

FIGURES 1–4. Larva Of Monocentroptilum badium. 1, Lateral view (arrOws shOw prOtuberances On mesOnOtum; 2, exuviae Of right half Of prOnOtum and mesOnOtum; 3, exuviae Of abdOminal sterna and terga; 4, subimaginal sterna and terga extracted frOm mature larva (tO shOw hypOdermal cOlOratiOn).

FIGURES 5–9. Larva Of Monocentroptilum badium. 5, labium; 6, maxilla (dOrsal view); 7, labium (at left ventral view, at right dOrsal view); 8–9, left and right mandible. AbbreviatiOns: ds1–ds3, dentisetae.

FIGURES 10–27. Larva Of Monocentroptilum badium. 10–16, tergalii Of I–VII pairs; 17, margin Of tergalius; 18, fOre leg; 19, claw (view frOm anteriOr side); 20, hind leg; 21, setae On apex Of its tibia; 22, claw (view frOm inner side); 23, exuviae Of half Of prOnOtum and mesOnOtum (thick line shOws area enlarged On Fig. 28); 24, setae On mesOnOtum; 25, seta On paired prOtuberances; 26, hind prOtOpterOm (the same scale as Fig. 23); 27, part Of head with clypeus, bases Of antennae, median Ocellus and frOntal suture.

FIGURES 28–31. Larval exuviae Of Monocentroptilum badium. 28, fragment Of mesOnOtum (Outlined On Fig. 23); 29, fragment Of cercus; 30, fragment Of tergum VIII; 31, paraprOct (all at the same scale).

FIGURES 32–39. Monocentroptilum badium. 32, anteriOr part Of male imagO with subimaginal exuviae; 33, head and thOrax Of male imagO; 34, abdOmen Of male imagO (spread On slide); 35, had and thOrax Of female imagO; 36, female imagO; 37–38, exuviae Of fOre and hind legs Of female subimagO; 39, exuviae Of hind tarsus Of female subimagO.

FIGURES 40–43. Monocentroptilum badium. 40–41, fOre and hind wings; 42, head and mesOnOtum Of male imagO; 43, subimaginal exuviae Of left pOstsubalar sclerite and laterOpOstnOtal crest.

FIGURES 44–47. Male genitals Of Monocentroptilum badium. 44, develOping subimaginal genitals, fOlded under larval cuticle; 45, subimaginal exuviae Of gOnOstyli; 46, imaginal genitals Of the same specimen (gOnOduct shOwn by dOtted lines, muscles shOwn by interrupted lines, internal parts Of penis shOwn by interrupted lines and dOtted); 47, its left unistyliger, tO shOw muscles. AbbreviatiOns: 1–3, segments Of gOnOstylus; gv, gOnOvectis; m.sg, median sternO-styligeral muscle; pgs, larval prOtOgOnOstylus; usg, unistyliger.

FIGURES 48–52. Male imaginal genitals Of Monocentroptilum badium. 48–49, specimen with prOtracted gOnOvectes: 48, with fOcus On internal parts, including gOnOvectes; 49, with fOcus On ventral surface, including unistyligers and median styligeral sclerite; 50–51, specimen with retracted gOnOvectes: 50, with fOcus On gOnOvectes and penial bridge; 51, with fOcus On median styligeral sclerite and median sternO-styligeral muscle; 52, gOnOstyli.

FIGURES 53–58. Eggs Of Monocentroptilum badium.