Procloeon (Oculogaster) cylindroculum Kimmins 1956

Kluge, Nikita J., 2016, A new subgenus Oculogaster subgen. n. for viviparous representatives of Procloeon s. l., with discussion about status of the generic name Austrocloeon Barnard 1932 and the species name africanum Esben-Petersen 1913 [Cloeon] (Ephemeroptera, Baetidae), Zootaxa 4107 (4), pp. 491-516 : 495-503

Procloeon (Oculogaster) cylindroculum Kimmins 1956

( Figs 1–42 )

? Austrocloeon africanum: Barnard 1932: 217 (♀ imago, larva) (non Cloeon africanum Esben-Petersen 1913 );

? Procloeon africanum: Kimmins 1956: 866 ; Gillies 1997: 247;

Procloeon cylindroculum Kimmins 1956: 865 (♂ imago); Kimmins 1960: 341 (♀ imago, ♂ and ♀ subimago); Kimmins 1971 (holotype); Gillies 1997: 247 (♀ imago, larva);

Cloeon cylindroculum: Demoulin 1970: 55 ; Gillies 1979: 155 (♂ imago); Gillies 1980: 145 (♂ and ♀ imago, larva); Gillies 1985: 8;

? Procloeon sylvicola Gillies 1997: 248 (♀ imago, ♂ subimago, larva).

Material examined. ZAMBIA, River Luangwa near bridge, 2–7.VIII.2014, coll. N. Kluge & L. Sheyko: 3 L-S-I♂, 1 L/S♂, 3 L-S♀; River Zambezi above Victoria Falls, 25–31.VIII.2014, coll. N. Kluge & L. Sheyko: 1 I ♀ (filled with embryos), 15 I ♀ (empty, without embryos). UGANDA: River Victoria Nile at Bujagali Falls, 6–10.VII.2007, coll. N. Kluge: 1 L-S-I♀, 1 L♀, 1 L/S♂, 2 S-I♀; Lake Victoria in Jinja, 6–10.VII.2007, coll. N. Kluge: 147 I♂, 5 S♂, 3 I ♀ (filled with embryos), 13 S♀; Entebbe, airport, 5.IX.2007, coll. N. Kluge: 2 I ♂, 2 S-I♀. MALI: River Bafing near Manantali, August– February 1990, 1991 and 1992, coll. W. Tobias & D. Tobias: 113 I♀ (partly with embryos), 1 S♂.

Descriptions. Larva. CUTICULAR COLORATION. Head with diffusive brownish and colorless areas. Pronotum and mesonotum ocher or brownish with diffusive lighter and darker areas; cuticle of fore protoptera either nearly unicolor, or with darker brown stripes along convex veins and stripes lighter than background along concave veins ( Fig. 26 ). Metanotum and thoracic pleura with diffusive colorless and brownish areas, thoracic sterna colorless. Legs colorless, with diffusive brown bands in distal part of femur, in proximal part of tibia and in proximal part of tarsus. Abdominal terga with variable maculation; abdominal sterna lighter than terga, either unicolor, or with diffusive lighter and darker areas ( Figs 23–25 ). Caudalii ocher with posterior margin of each 4-th segment brown ( Fig. 21 ).

HYPODERMAL COLORATION. Mature larva with markings characteristic for winged stages: mature male larva with reddish coloration on posterior part of abdominal tergum VII and terga VIII–IX; middle terga either without hypodermal markings, or with pair of reddish spots on abdominal tergum IV ( Fig. 35 ); mature female larva with pair of curved stripes along thorax and abdomen ( Fig. 36 ).

SHAPE AND SETATION. Mandibles with incisor and kinetodontium fused more than to middle, with ventral denticle well-developed; incisor of right mandible with 2nd denticle shortest; right prostheca apically with 3–6 short parallel processes ( Figs 8–10 ). Maxillary palp 2-segmented ( Fig. 28 ). Labium with glossae and paraglossae of subequal size, palp with median angle moderately projected (as in Figs 47–48 ). Femora with very small spine-like setae on outer and inner sides, with 2 (rarely 3) larger pointed spine-like setae on outer side near apex ( Fig. 20 ). Claws moderately long, with two rows of minute denticles in proximal part and two rows of larger denticles reaching mid-length of claw ( Fig. 19 ). Hind protoptera completely absent. Lateral spines on abdominal segments V–IX, occasionally also on segments IV and III, with numbers varying on abdominal segments III–IX as follows: III 0–1, IV 0–1, V 2–4, VI 3–4, VII 3–5, VIII 5–7, IX 5–7. Posterolateral spines present on segments II–IX, being minute on anterior segments. Posterior margin of abdominal tergum I with few small sparse spine-like pointed denticles; posterior margins of terga II–X with larger spine-like pointed denticles of unequal length; tergum X with sublateral denticles longest ( Fig. 21 ; as in Fig. 61 ). Abdominal terga with short scales in wide semilunar or Wshaped non-operculated sockets, with sparse simple fine setae (similar to Fig. 62 ). Posterior margins of abdominal sterna I–V smooth, posterior margins of sterna VI–IX and paraprocts with spine-like pointed denticles of unequal length. Abdominal sterna with sparse scales and sparse fine setae; in lateral areas of sterna both simple and bifid fine setae vary from small to very long, located sparsely and irregularly, not forming rows or groups (as in Fig. 63 ). Tergalius I with costal rib very short and lacking denticles; tergalii II–VI with 2–5 denticles on apex of costal rib, tergalius VII with 4–10 denticles on costal rib; dorsal lamella present either on tergalii I–VI ( Figs 1–7 ), or I–V ( Figs 11–17 ). In distal part of cercus spine on lateral side of each segment subequal or 1.5 times longer than next segment ( Fig. 22 ).

Subimago. CUTICULAR COLORATION. Head colorless. Pronotum with diffusive light brownish and colorless areas. Mesonotum light brownish with sutures darker brown, with large colorless areas occupying anterior part of submedioscutum and posterior scutal protuberance ( Fig. 27 ). Thoracic pleura at most colorless, with some sclerites light brownish ( Fig. 37 ). Legs nearly colorless. Abdomen very light brownish with pair of diffusive darker triangular maculae adjacent to posterior margin of each tergum. Caudalii colorless. HYPODERMAL COLORATION. As in imago.

TEXTURE. On fore leg of male and female 1st tarsal segment covered mainly with microtrichiae (as tibia), at apex with pointed microlepides; all other tarsal segments entirely covered with pointed microlepides.

Imago, male ( Figs 33–34 ). Head brown with ocher. Turbinate eyes cylindrical or widened at apex; color varies from orange to dark red. Thorax brown; sterna somewhat lighter than terga; membranes of pleura either ocher, or white. Legs pale ocher or whitish. In reared specimen from Zambia, ratio femur / tibia / tarsal segments on fore leg 100:140:5:72:44:23:16, on middle and hind leg 85:80:35:12:3:14. Middle and hind legs without apical spine of 1st+2nd tarsomere, with single apical spine on primary 3rd tarsomere. Fore wing widest at proximal part; membrane colorless, veins light brown; pterostigma with one oblique vein, no other veins in costal field (among more than 300 specimen examined, only 4 specimens have 2 or 1½ veins in pterostigma of one wing). Marginal intercalary present at least in each 2nd space, namely in spaces located behind convex vein; in spaces located behind concave veins marginal intercalary either absent ( Figs 32 , 33 ), or present. Hind wing absent. Abdominal terga I–VI translucent, whitish, either unicolor, or with posterior margins slightly darkened; tergum IV either as others ( Fig. 34 ), or with pair of red or brown spots ( Fig. 33 ), or with unpaired transverse red or brown spot. Tergum VII with anterior part translucent and whitish as previous segments, posterior part brown; terga VIII–X brown. Sterna I–VII translucent, whitish, either unicolor, or with posterior margin darkened by brown. Sterna VIII, IX, styligers and gonostyli ocher-brownish. Median projection of penis semicircular ( Fig. 30 ). Cerci either entirely colorless ( Fig. 34 ), or with dark bands formed by brown hypodermal pigmentation in distal part of each 4th segment ( Fig. 33 ).

Imago, female ( Figs 36 , 38–42 ). Head relatively wide, distance between eyes exceeds eye length; eyes only slightly elevated above head surface. Head, thorax and abdomen ocher with contrasting red, purple, brown or/and black hypodermal strip of composite form, stretching along lateral side of body (along thoracic pleura and along lateral parts of abdominal terga) from prothorax to tip of abdomen. In fresh specimens dorsal margin of this stripe can be bordered by contrasting white stripe ( Fig. 40 ); on posterior margins of abdominal terga IV and VIII lateral stripes turned medially ( Figs 36 ). Mesonotum either unicolor ocher, or with contrasting pigmented stripes on lateral areas ( Fig. 40 ). All legs with single apical spine on primary 3rd tarsomere. Wings as in male. Cerci colorless with contrasting dark brown or black bands formed by hypodermal pigmentation of each 4th or each 2nd segment.

Egg. Without rigid chorion; embryos are developed inside female imago, so that mature female imago looks maculated because of black eyes and ocelli of embryos visible through its integument ( Fig. 41 ).

Dimension. Fore wing length of male and female 4–5 mm.

Variability. Turbinate eyes of male imago. Gillies (1979) reported variability in shape of turbinate eyes of P. cylindroculum , which in some populations are mainly tall and cylindrical (height to width about 1.5:1), and in others mainly broad (height to width about 1:1). Most specimens examined by me have intermediate shape of turbinate eyes ( Figs 33–34 ).

Marginal intercalaries. In the original description wing on P. cylindroculum is figured as having marginal intercalaries in each space ( Kimmins 1956: Fig. 2 ). Gillies, based on reexamination of holotype and paratypes and examination of other material, reported that actually marginal intercalaries are present in alternated spaces ( Gillies 1980: 147). Specimens examined by me, have marginal intercalaries at least in spaces located behind convex veins; spaces behind concave veins are either empty ( Figs 32 ), or some of them have intercalary.

Coloration of male imago and subimago. According to the original description of P. cylindroculum based on male imagoes from Malawi ( Nyasaland), abdominal tergum IV has no pair of reddish spots, and cerci have no dark bands ( Kimmins 1956). According to the additional description based on material from Entebbe and Jinja in Uganda, most male specimens have the same color, but some specimens have pair of reddish brown spots on tergum IV and annulated cerci ( Kimmins 1960). Among 152 specimens from the same locality (Jinja) examined by me, most specimens have no spots on tergum IV ( Fig. 34 ), and 23 specimens have pair of reddish or brownish spots, contrasting in some specimens and poorly expressed in others; all preserved cerci have no dark bands ( Fig. 34 ). Among 4 males collected in Zambia (three imagoes reared from larvae and one subimago extracted from larva), 3 specimens have a pair of well-expressed spots on abdominal tergum IV ( Figs 33, 35 ), and one specimen has less distinct unpaired transverse macula on the same place; cerci of all four specimens have dark bands ( Fig. 33 ), which are less contrasting than in females collected in Uganda and Zambia ( Fig. 40 ).

Coloration of female imago and subimago. Gillies (1980) reported variability in coloration of freshly caught females, some of which have no red lateral lines on thorax and abdomen. Among specimens examined by me, all females collected in Uganda and Zambia, have these lines. Females without this coloration are found among specimens from Mali; fixation of these specimens was not well, and their initial coloration is unknown.

Larval tergalii. All three examined larvae from Victoria Nile have tergalii large, greatly widened, dorsal lamella being present on tergalii I–VI ( Figs 1–7 ). Among seven examined larvae from Luangwa, only five specimens have tergalii preserved; their tergalii are relatively small, with small dorsal lamella on tergalii I–V only ( Figs 11–17 ). Larvae described by Barnard (1932) under the name “ Austrocloeon africanum ”, according to his description, have dorsal lamella either on tergalii I–V, or on tergalii I–VI. On the drawing made by Gillies (1980: Fig. 20 ) tergalii of Cloeon cylindroculum are wide, tergalii I–VI with dorsal lamella; tergalius VII is figured wrongly, probably being either overturned, or damaged. For the newly described species Procloeon silvicola, Gillies (1997) reported presence of dorsal lamellae on tergalii I–IV only; this conclusion was based on one larval skin and was not suggested as a character separating P. sil vicol a from P. cylindroculum . In the same paper tergalius III of C. cylindroculum is figured as narrow and having small dorsal lamella ( Gillies 1985: Fig. 2 ). Similar variations of size and shape of tergalii, and presence/absence of dorsal lamella on tergalii of posterior pairs, are usual for other species of Procloeon , for which long series of larvae were examined. For example, in Procloeon macronyx Kluge & Novikova 1992 dorsal lamella can be larger or smaller, present or absent on tergalius VI ( Kluge & Novikova 1992: Figs 1–15 ); in P. heterophyllum Kluge & Novikova 1992 dorsal lamellae vary from absent on all tergalii to present on tergalii I–V (110 larvae from one small stream were examined).

Figures

FIGURES 1 – 10. Procloeon (Oculogaster) cylindroculum, larva. 1 – 7, tergalii of I – VII pairs (specimen from Uganda); 8, 9, apices of left and right mandibles, dorsal view; 10, apex of right mandible, apical view. Abbreviations: in 1, in 2, in 3, in 4, denticles of incisor; in-V, ventral denticle of incisor; kd 1, kd 2, kd 3, denticles of kinetodontium.

FIGURES 11 – 20. Procloeon (Oculogaster) cylindroculum, larva. 11 – 17, tergalii of I – VII pairs (specimen from Zambia); 18, frontal suture; 19, claw; 20, fore leg, anterior view (fine setae not shown; dots show bases of fine setae forming regular rows on apical part of femur, proximal part of tibia and proximal part of tarsus).

FIGURES 21 – 29. Procloeon (Oculogaster) cylindroculum, larvae from Zambia. 21, cercus and paracercus; 22, distal part of cercus; 23 – 25, abdominal terga and sterna; 26, right half of pronotum and mesonotum; 27, subimaginal exuviae of right half of mesonotum; 28, maxilla; 29, labrum.

FIGURES 30 – 32. Procloeon (Oculogaster) cylindroculum from Zambia. 30, genitals of male imago (at left half gonovectal muscles shown by interrupted lines, hidden part of penis shown by interrupted line and dotted, gonostylar muscle not shown; at right half gonostylar muscle shown by interrupted lines, gonovectal muscles not shown; median styligeral muscle shown by interrupted lines, areas of anterior attachment of median paraproctal muscles shown by dotted lines). 31, exuviae of subimaginal genitals; 32, wing. Abbreviations: 1, 2, 3, segments of gonostylus; mIX-X, areas of anterior attachment of median paraproctal muscles (i. e., muscles going from sternum IX to common base of paraprocts); usg, unistyliger.

FIGURES 33 – 37. Procloeon (Oculogaster) cylindroculum. 33, 34, male imagoes; 35, subimaginal abdomen extracted from mature male larva; 36, subimaginal abdomen extracted from mature female larva; 37, subimaginal exuviae of postsubalar sclerite and lateropostnotal crest (33, 35 – 37, specimens from Zambia; 34, specimen from Uganda).

FIGURES 38 – 42. Procloeon (Oculogaster) cylindroculum, female imago. 38, head and prothorax in Canadian balsam with embryos visible inside; 39, enlarged embryo with focus on median ocellus and mandibles; 40, mature female imago free of embryos; 41, abdomen of female imago with embryos (black eyes and ocelli visible through integument); 42, embryo extracted from female imago (38, 39, 41, 42, from Uganda; 40, from Zambezi). Abbreviations: md, mandibles; oc, future facetted eye; ocl. l., lateral ocellus; ocl. m., median ocellus.

FIGURES 43 – 48. Procloeon (Oculogaster) album sp. n., larva. 43, labrum, 44, 45, apices of left and right mandibles; 46, maxilla, dorsal view; 47, half of labium, ventral view; 48, the same, dorsal view. Abbreviations: ds 1, ds 2, ds 3, dentisetae; in 1, in 2, in 3, in 4, denticles of incisor; in-V, ventral denticle of incisor; kd 1, kd 2, kd 3, denticles of kinetodontium.

FIGURES 59 – 64. Procloeon (Oculogaster) album sp. n., larva. 59, paracercus and cercus (with subimaginal cercus inside); 60, distal part of cercus; 61, posterior margin of abdominal tergum X; 62, fragment of abdominal tergum III; 63, fragment of abdominal sternum VI; 64, tergalius VI (arrow shows additional middle rib) (59, 60, holotype).