Procloeon (Oculogaster) barnardi, Kluge, 2020

Kluge, Nikita J., 2020, Review of Oculogaster Kluge 2016 (Ephemeroptera, Baetidae, Procloeon Bengtsson 1915), Zootaxa 4820 (3), pp. 401-437 : 405-414

Procloeon (Oculogaster) barnardi sp. n.

( Figs 1–42 )

Austrocloeon africanum: Barnard 1932: 217 (imago, larva); Barnard 1940: 623; Crass 1947: 57; Harrison 1950: 113; Harrison & Agnew 1962: 278: Table 4, 289; Chutter 1963; Oliff & King 1964: 576: Table 3a (non Cloeon africanum Esben-Petersen 1913). Procloeon africanum: Kimmins 1956: 866 ; Gillies 1997: 247. Cloeon africanum: Palmer, O’Keeffe, Palmer, Dunne & Radloff 1993: 448 (non Esben-Petersen 1913). Procloeon (Oculogaster) cylindroculum (partim): Kluge 2016: 495.

Etymology. The species is named in honour of K.H. Barnard, who described it under the name « Austrocloeon africanum ».

Material examined. Holotype ( AM): L-S-I ♂ {specimen [III](10)2019}, SOUTH AFRICA, Cape Winelands District (= Boland District), Jonkershoek Valley , Eerste River upstream Stellenbosch , Swiss Club (5 km SE Stel-lenbosch ), 33°57′30′′S, 18°55′E, 22.I.2019, coll. N. Kluge & L. Sheyko. Paratypes ( ZIN): same locality and col-lectors, 18–19.I.2019: 1 L/S ♂, 2L/S ♀, 3 larvae; 8–11.II.2019: 2 L/S ♂, 2 L-S ♀, 5 larvae; Winelands District (= Boland District ), Wolwekloof River near fall to Witte River ( Bain’s Kloof ), Tweede Tol campsite, 33°34′S 19°08′E, 20–22.I.2019, coll. N. Kluge & L. Sheyko: 1 L/S ♀, 1 larva; Overberg District , Wolfkloof, Keurbooms River (8 km WNW Swellendam ), 33°59′S 20°22′30”E, coll. N. Kluge & L. Sheyko: 25–26.I.2019: 1 larva; Garden Route district (= Eden district ): Cango Mountain resort (20 km NNE Oudshoorn ), 33°25′S 22°16′E, 28.I–2.II.2019, coll. N. Kluge & L. Sheyko: 1 L/S ♂, 1 L-S-I ♀, 1 L-S ♀; lodge «Wild Spirit», tributary of Bobbejaans River (5 km NW Nature’s Valley), 33°57′S 23°31′30”E, 3rd pool from waterfall, 3–7.II.2019, coll. N. Kluge: 3 L-S-I ♀, 1 L-S ♀, 3 larvae.

Descriptions. Larva. CUTICULAR COLORATION. Head with brownish and colorless areas. Pronotum and mesonotum ocher or brownish with lighter and darker areas ( Figs 1 , 11, 13, 15, 16 ); mesonotum with more-orless large blanks approximately corresponding to blanks on submedioscutum and posterior scutal protuberance of subimaginal cuticle ( Fig. 1 ); cuticle of fore protoptera either nearly unicolor, or with darker brown stripes along convex veins and stripes lighter than background along concave veins ( Fig. 13 ). Metanotum and thoracic pleura with colorless and brownish areas, thoracic sterna colorless. Legs colorless or light ocher, 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, different on different segments; most or all terga with submedian pair of blanks, either corresponding to sigilla, or larger than sigilla; terga IV and VII more-or-less lighter than others ( Figs 2 , 10, 12, 14, 16 ). Abdominal sterna lighter than terga, either unicolor, or with lighter and darker areas. Caudalii ocher with posterior margin of every 4th segment brown ( Fig. 8 ).

HYPODERMAL COLORATION. Mature larva with markings characteristic for winged stages, similar in male and female: abdominal terga II, IV and VII with large W-shaped reddish-brown macula ( Figs 4, 6–7 ); abdominal sterna with lateral longitudinal brown maculae ( Figs 6–7 ), whose size varies individually (as in Figs 37, 38 ).

SHAPE AND SETATION. Labrum as in other Oculogaster (as in Figs 49–50 ; Kluge 2016: figs 29, 43). 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 [as in P. (O.) niger sp. n. ( Fig. 52 ) and P. (O.) cylindroculum ( Kluge 2016: figs 9–10)]. Maxillary palp 2-segmented ( Barnard 1932: fig. 9e; as in Fig. 54 ). Labium with glossae and paraglossae of subequal size, palp with median angle moderately projected ( Barnard 1932: fig. 9d; as in Figs 55–56 ). Femora with very small spine-like setae on outer and inner sides, with 2 spine-like apical setae located in plane of leg; apical setae pointed or blunt, larger than other spine-like setae or equal to them ( Fig. 17 ). Claws moderately long, with two rows of denticles, minute in proximal part and larger more distally, reaching mid-length of claw ( Fig. 29 ). Hind protoptera completely absent. Lateral spines on abdominal segments V–IX, spines sometimes present only on some of these segments; segment IX with 2–7 spines on one side, other segments with equal or less number of spines ( Figs 2–3 ). 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 ( Fig. 3 ); on tergum IX row of denticles interrupted medially, behind pair of submedian setae (as in Fig. 47 ). Abdominal terga with short scales in wide semilunar or W-shaped non-opercula-bearing sockets, with sparse simple fine setae; one pair of bifurcate setae (as in Fig. 48 ) near midlength of each tergum VIII–IX and one pair of bifurcate setae near posterior margin of each tergum VII and IX ( Fig. 3 ). Posterior margins of abdominal sterna I–V smooth, posterior margins of sterna VI–IX and paraprocts with spine-like pointed denticles of unequal length (as in Fig. 47 ). 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 regular rows. Tergalius I with costal rib very short and lacking denticles; costal rib on tergalii II–VII longer, either without denticles or with few small denticles on apex; dorsal lamella present either on tergalii I–VI, I–V, or I–IV ( Figs 19–28 ). In distal part of cercus spine on lateral side of each segment subequal to or 1.5 times longer than next segment ( Fig. 9 ).

Subimago. CUTICULAR COLORATION. Head colorless. Pronotum with brown and colorless areas. Mesonotum brown with sutures darker brown, with large colorless areas occupying anterior part of submedioscutum and posterior scutal protuberance ( Fig. 32 ). Thoracic pleura mostly colorless, with some sclerites brown ( Fig. 33 ). Legs nearly colorless, with base of tibia brown, sometimes brownish stripes on femur. Abdomen very light brownish with sigilla colorless. Caudalii colorless.

HYPODERMAL COLORATION. As in imago, similar in male and female (see below).

TEXTURE. On fore leg of male and female 1st tarsal segment covered partly with microtrichia (as tibia), partly with pointed microlepides; all other tarsal segments entirely covered with pointed microlepides (as in Fig. 42 ).

Imago, male ( Figs 30–31 ). Head ocher with brown. Antenna pale ocher, scapus and pedicellus with small brown spot at apex on lateral and median sides. Turbinate eyes widened apically; facetted surface yellow, stem orange. Pronotum ocher with brown maculae; propleura and prosternum brown, articulations pale ocher. Meso- and metathorax with sclerites brown, membranes pale ocher. Legs pale ocher or whitish. In holotype, ratio femur / tibia / tarsal segments (mm) on fore leg 0.96: 1.20: 0.05: 0.52: 0.35: 0.19: 0.14; on middle and hind leg 0.85: 0.73: 0.28: 0.09: 0.04: 0.14. Middle and hind legs without apical spine on 1st+2nd tarsomere, with single apical spine on primary 3rd tarsomere (as in Fig. 42 ). Wing with membrane colorless, veins ocher; subcostal vein proximad of costal brace colored with brown. Pterostigma with one oblique cross vein; besides it, costal field with very slender cross vein belonging to middle cord of cross veins (as in female – Barnard 1932: fig. 8). Marginal intercalaries present in most of interspaces, both behind convex and concave longitudinal veins. Hind wing absent. Abdominal terga light ocher with large darker W-shaped maculae, contrastingly reddish-brown on terga II, IV and VII, less contrasting on other terga. Abdominal sternum I light brownish, with pair of round lateral brown maculae; sterna II–IX light ocher, with pair of longitudinal lateral brown stripes. Gonostyli pale ocher, penis brown. Median projection of penis semicircular ( Fig. 34 ). Cerci with alternating whitish and brown segments.

Imago, female ( Figs 36–39 ). Head relatively wide, distance between eyes exceeds eye length; eyes only slightly elevated above head surface. Head ocher, with or without brown markings. Pronotum ocher, with more or less extensive brown spots. Mesonotum either uniformly pale ocher ( Fig. 37 ), or with medioscutum darker, scutellum white and parascutellum brown ( Fig. 38 ). Postnotum either uniformly pale ocher, or with brown markings. Thoracic pleura and sterna ocher or light brownish, with brown and white maculae. Fore leg without apical spine on 2nd tarsomere, with single apical spine on primary 3rd tarsomere (as in Fig. 76 ); same on middle and hind legs (as in Fig. 42 ). Wings as in male (see above); on one wing of one specimen, pterostigma, besides one cross vein, with additional incomplete cross vein ( Fig. 41 ). Abdominal terga ocher with contrasting reddish-brown maculae: most extensive and more or less W-shaped maculae on terga II, IV and VII; median unpaired spot or stripe (either separate or incorporated into W-shaped macula) on terga II–VII; pair of submedian spots on all or some of terga II–VII; pair of zigzag ocher or brown bands along lateral margins of abdominal terga, connecting W-shape maculae of terga II, IV and VII. Abdominal sterna ocher, sterna I–IX with pair of contrasting reddish-brown lateral maculae: these maculae either round on sternum I and longitudinal wedge-like on sterna II–IX ( Fig. 36 ; Barnard 1932: fig. 9a), or wide and parallel-sided on all sterna I–IX ( Fig. 39 ). Cerci with alternating whitish and brown segments.

Egg. Without rigid chorion (viviparity).

Dimension. Fore wing length of male and female 4.5–5 mm (5–5.5 mm according to Barnard 1932).

Comparison. The larva of P. (O.) barnardi sp. n. has the same structure and cuticular coloration as P. (O.) cylindroculum . However, the hypodermal pigmentation of larva, subimago and imago is clearly different in these two species. While in P. (O.) cylindroculum the abdominal hypodermal pigmentation sharply differs in male and female ( Kluge 2016: figs 35–36), in P. (O.) barnardi sp. n. it is similar in both sexes ( Figs 30 , 37–38 ), especially in the subimaginal stage ( Figs 6–7 ). I was able to examine only one male imago of P. (O.) barnardi sp. n., but the characteristic hypodermal pigmentation of the male was examined also on 7 mature male larvae ( Figs 4, 6 ), so this character is assumed to be reliably species-specific.

In contrast to male P. (O.) cylindroculum , whose middle abdominal terga are either non-pigmented, or with one pair of small spots on tergum IV only ( Kluge 2016: figs 33–34), in male P. (O.) barnardi sp. n. all abdominal terga have large W-shaped maculae ( Figs 30–31 ). Male imaginal turbinate eyes of P. (O.) barnardi sp. n. are much wider that that of P. (O.) cylindroculum . Kimmins (1965) correctly reported that the male imago of P. (O.) cylindroculum differs by «more slender claspers» (i.e. gonostyli) (Kimmins 1965: fig. 2; Kluge 2016: fig. 30), while in P. (O.) barnardi sp. n. the second segment of gonostylus is relatively shorter and thicker ( Fig. 34 ; Barnard 1932: fig. 9i).

In contrast to female P. (O.) cylindroculum , whose abdominal terga have constant zigzag lateral bands expressed both in imago and subimago, and have no median maculae ( Kluge 2016; fig. 36), female P. (O.) barnardi sp. n. has median maculae on all or some terga, while zigzag lateral bands are expressed only in imago ( Figs 36–39 ), being absent in subimago and larva ( Fig. 7 ).

Comments. This species was described by Barnard (1932), who regarded it to be conspecific with Cloeon africanum Esben-Petersen 1913 and placed it in a newly established genus Austrocloeon Barnard 1932 . The species identification was based not on the holotype, but on «topotypes from Zululand» ( Barnard 1932: 219). The original description of africanum [ Cloeon ] was based on a single male imago. Its genitalia ( Esben-Petersen 1913: fig. 8) have nothing in common with the genitalia of the species described by Barnard (1932: fig. 9i) under the name « Austrocloeon africanum ». Because of this, I concluded that the genus-group name Austrocloeon (whose type species is africanum [ Cloeon ]) and the species name africanum should not be applied to the species described by Barnard under these names ( Kluge 2016). Recent examination of a male imago belonging to the Barnards’s « Austrocloeon africanum » reveals that it sharply differs from africanum [ Cloeon ] not only in genital structure, but in coloration as well: according to the original description, «2nd–6th segments of abdomen transparent, whitish and with a faint reddish tinge; the hind borders of the segments darker. The 7th–9th segments reddish brown on the dorsal surface, whitish on the ventral» ( Esben-Petersen 1913: 184); such coloration occurs in many species of Baetidae , but not in P. (O.) barnardi sp. n. described above. Judging by the structure of gonostyli ( Esben-Petersen 1913: fig. 8), the species africanum [ Cloeon ] can be a member of Rhithrocloeoninae Kluge 2012, which belong to the plesiomorphon Protopatellata Kluge & Novikova 2011 ( Kluge 2016). Recently, larvae of an unknown two-winged protopatellatan species were found in South Africa; possibly, they belong to the true africanum [ Cloeon ] ( Kluge, 2020b).

Barnard (1932) described the imago of « Austrocloeon africanum » not indicating its sex; actually this description belongs to the female only, more precisely to the light form of female (the same as in Figs 36–37 ). Besides the drawings of the female imaginal abdomen ( Barnard 1932: figs 9a–b), Barnard gave also a drawing of the male imaginal gonostylus (ibid., Fig. 9i ). Other characters of male imago or subimago had not been reported.

Barnard (1932) also described larvae of this species and noted «two varieties» of their abdominal coloration; probably, the first of them, with all terga similarly ornamented ( Barnard 1932: fig. 9c) represents a combination of cuticular and hypodermal coloration ( Fig. 4 ), and the second one, with terga IV and VII much lighter than others ( Barnard 1932: fig. 9h), represents the cuticular coloration solely ( Figs 2 , 16 ).

Since the paper by Barnard (1932) was published, a variety of authors have applied the name « Austrocloeon africanum » to the species described in this paper, including some (e.g., Harrison & Agnew 1962; Oliff & King 1964) who erroneously reported its authorship as « Austrocloeon africanum Barnard ».

The coloration of winged males of this species was not described. Kimmins (1956), comparing the newly described species Procloeon cylindroculum with what he called « Procloeon africanum (E.-P.)» (actually P. barnardi sp. n.) wrote that «it differs from that species in the translucent middle segments of the abdomen», but he did not report the source of information about abdomen coloration of the male « P. africanum ». Recent examination of reared male imago and male subimagines extracted from mature larvae reveals that the male of this species has middle segments of the abdomen intensively pigmented, which is different from P. cylindroculum .

Figures

FIGURES 1–7. Procloeon (Oculogaster) barnardi sp. n. 1–6, male larva ready to moult to subimago: 1–2, larval cuticle detached from thorax and abdomen; 3, fragment of abdomen (arrows show bases of bifurcate setae similar to Fig. 48); 4, intact specimen (IV–IX, abdominal segments); 5, extracted subimaginal thorax; 6, extracted subimaginal abdomen; 7, same, female.

FIGURES 8–16. Larvae of Procloeon (Oculogaster) barnardi sp. n. 8–9, caudalii; 10–15, exuviae of abdomen and pronotum with mesonotum of three specimens (14–15, holotype); 16, young larva.

FIGURES 17–18. Larva of Procloeon (Oculogaster) barnardi sp. n., middle leg. 17, apex of femur and base of tibia, anterior view (patella-tibial suture and bases of fine setae are visible as light markings on darker background); 18, more distal part of tibia, posterior view (with continuation of patella-tibial suture visible as light line).

FIGURES 19–29. Larvae of Procloeon (Oculogaster) barnardi sp. n. 19–25, tergalii I–VII; 26–27, tergalii V of other specimens; 28, tergalius VII of another specimen; 29, claw (holotype).

FIGURES 30–33. Male Procloeon (Oculogaster) barnardi sp. n. (holotype). 30–31, imago; 32, exuviae of subimaginal mesonotum; 33, exuviae of subimaginal pleuron.

FIGURES 34–35. Male Procloeon (Oculogaster) barnardi sp. n. (holotype). 34, genitalia of imago (penis dotted; gonostylar muscle not shown at right, penial muscles not shown at left); 35, their subimaginal exuviae.

FIGURES 36–42. Female Procloeon (Oculogaster) barnardi sp. n. 36–39, imagines; 40–41, veins of pterostigma; 42, hind tarsus of subimago.

FIGURES 49–56. Larva of Procloeon (Oculogaster) niger sp. n. (holotype): 49–50, labrum with focus on ventral and dorsal sides; 51–52, left and right mandibles; 53–54, maxilla (ds1–ds3, dentisetae); 55–56, labium with focus on dorsal and ventral sides.

FIGURES 43–48. Larval exuviae of Procloeon (Oculogaster) niger sp. n. 43–44, caudalii; 45, abdomen; 46, half of pronotum and mesonotum; 47, male uromeres IX–X; 48, fragment of abdominal tergum VIII (arrow shows long bifurcate seta near midlength) (43–46, holotype).

FIGURES 73–77. Female Procloeon (Oculogaster) niger sp. n. 73–74, imago; 75, imaginal abdomen; 76–77, subimaginal exuviae of fore and middle tarsi (arrows show spines; 1st–5th, initial tarsomeres).