Procloeon (Oculogaster) niger, Kluge, 2020

Kluge, Nikita J., 2020, Review of Oculogaster Kluge 2016 (Ephemeroptera, Baetidae, Procloeon Bengtsson 1915), Zootaxa 4820 (3), pp. 401-437: 414-420

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Procloeon (Oculogaster) niger

sp. n.

Procloeon (Oculogaster) niger   sp. n.

( Figs 43–77 View FIGURES 43–48 View FIGURES 49–56 View FIGURES 57–66 View FIGURES 67–70 View FIGURES 71–72 View FIGURES 73–77 )

Etymology. Allusion to the uniformly dark coloration of larva and uniform dark color pattern on abdominal terga in male and female imago.

Material examined. Holotype ( AM): L-S-I ♂ {specimen [XVIII](3)2019}, SOUTH AFRICA, Garden Route district (= Eden district ), lodge «Wild Spirit», tributary of Bobbejaans River (5 km NW Nature’s Valley). 33°57’S 23°31′30′′E, 3rd pool from waterfall, 7.II.2019, coll. N. Kluge. GoogleMaps   Paratypes ( ZIN): same locality and collector, 39.II.2019: 2 L-S-I ♂, 3 L-S ♂, 1 L-S-I ♀, 1 L-S ♀, L/S ♂, 19 larvae GoogleMaps   .

Descriptions. Larva. CUTICULAR COLORATION. Head, thorax, legs and abdomen nearly uniformly brown ( Figs 45–46 View FIGURES 43–48 ). Caudalii lighter, brown proximally and near apex, with posterior margin of each 4th segment brown ( Fig. 43 View FIGURES 43–48 ).

HYPODERMAL COLORATION. Mature larvae of both sexes with large lateral dark markings on abdominal terga, as in winged stages (as in Figs 67–68 View FIGURES 67–70 , 73–75 View FIGURES 73–77 ).

SHAPE AND SETATION. Labrum as in other Oculogaster   ( Figs 49–50 View FIGURES 49–56 ). 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 2–6 short parallel processes ( Figs 51–52 View FIGURES 49–56 ). Maxillary palp 2-segmented ( Fig. 54 View FIGURES 49–56 ). Labium with glossae and paraglossae of subequal size, palp with median angle moderately projected ( Fig. 55–54 View FIGURES 49–56 ). 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 (as in Fig. 17 View FIGURES 17–18 ). Claws moderately long, with two rows of denticles, minute in proximal part and larger more distally, exceeding mid-length of claw ( Fig. 66 View FIGURES 57–66 ). Hind protoptera completely absent. 1–4 lateral spines on posterior part of abdominal segment IX only ( Fig. 47 View FIGURES 43–48 ). Posterolateral spines present on segments VI–IX, being minute on most anterior of these segments. Posterior margin of abdominal tergum I with few sparse small spine-like pointed denticles; posterior margins of terga II–X with spine-like pointed denticles of unequal length, shorter on anterior terga and longer on posterior terga ( Fig. 47 View FIGURES 43–48 ); on tergum IX row of denticles interrupted medially, behind pair of submedian setae ( Fig. 47 View FIGURES 43–48 ). 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 ( Fig. 48 View FIGURES 43–48 ) near midlength of each tergum VIII–IX and one pair of bifurcate setae near posterior margin of each tergum VII and IX (as in Fig. 3 View FIGURES 1–7 ). Posterior margins of abdominal sterna I–IV smooth, posterior margin of sternum V with few minute denticles, 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 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–V, or II–IV ( Figs 57–65 View FIGURES 57–66 ). Cerci with especially long and slender distal portions lacking swimming setae and lateral spines ( Fig. 43 View FIGURES 43–48 ). In distal part of cercus (proximad of slender setae-less distal portion) spine on lateral side of each segment subequal or slightly longer than next segment ( Fig. 43 View FIGURES 43–48 ).

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. 70 View FIGURES 67–70 ). Thoracic pleura mostly colorless, with some sclerites brown ( Fig. 69 View FIGURES 67–70 ). Legs nearly colorless, with base of tibia brown, sometimes brownish stripes on femur. Abdomen very light brownish with sigilla colorless. Caudalii light brownish.

TEXTURE. On fore leg of male and female, 1st tarsal segment covered partly with microtrichia (as in tibia), partly with pointed microlepides; all other tarsal segments entirely covered with pointed microlepides ( Figs 7677 View FIGURES 73–77 ).

Imago, male ( Figs 67–68 View FIGURES 67–70 ). Head ocher with brown. Antenna pale ocher, joining of scapus and pedicellus brown. Turbinate eyes widened apically; facetted surface and dorsal part of stem light yellow, ventral part of stem brown. Thorax brown, with sterna lighter yellowish, pleura with longitudinal white and darker brown bands. Legs light yellow. In paratype, ratio femur / tibia / tarsal segments (mm) on fore leg 1.10: 1.55: 0.05: 0.72: 0.60: 0.30: 0.17; on middle and hind leg 0.92: 0.88: 0.30: 0.13: 0.05: 0.15. Middle and hind legs normally with 2 apical spines: on 1st+2nd and on primary 3rd tarsomeres (as in Fig. 77 View FIGURES 73–77 ) (among specimens examined, only in holotype one of these spines lacking on some legs). 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. Marginal intercalaries present in most of interspaces, both behind convex and concave longitudinal veins. Hind wing absent. Abdominal terga mostly brown; terga II–VI with lateral areas dark brown, median area lighter, with pair of light spots adjacent to anterior margin, light submedian sigilla and unpaired light spot adjacent to posterior margin; tergum VII dark brown with pair of light spots adjacent to anterior margin and light submedian sigilla; terga VIII–X dark brown with light submedian sigilla. Abdominal sterna light ocher, with pair of longitudinal lateral brown stripes. Gonostyli pale ocher, penis brown. Median projection of penis semicircular ( Fig. 71 View FIGURES 71–72 ). Cerci whitish, with brown apex of each segment or every 2nd segment.

Imago, female ( Figs 73–76 View FIGURES 73–77 ). Head moderately wide, distance between eyes subequal to eye length; eyes only slightly elevated above head surface. Head ocher, with reddish brown and white stripes. Pronotum ocher, with small brown spots. Mesonotum ocher, bordered with reddish-brown and white stripes. Thoracic pleura ocher with wide white and brown longitudinal bands. Sterna and legs light yellow. Fore leg without apical spine on 2nd tarsomere, with single apical spine on primary 3rd tarsomere ( Fig. 76 View FIGURES 73–77 ); middle and hind legs each with 2 spines ( Fig. 77 View FIGURES 73–77 ) (as in male – see above). Wings as in male (see above). Abdominal terga with peculiar contrasting ornament gradually changing from tergum II to tergum IX, including dark reddish-brown lateral areas, medial ocher area and paired white spots; terga VIII–IX with median reddish-brownish stripe; tergum X reddish-brownish ( Fig. 73, 75 View FIGURES 73–77 ). Abdominal sterna ocher, with pair of longitudinal lateral reddish-brown stripes ( Fig. 74 View FIGURES 73–77 ). Cerci as in male (see above) ( Fig. 73–74 View FIGURES 73–77 ).

Egg. Without rigid chorion (viviparity).

Dimension. Fore wing length of male 4–5 mm, female 6 mm.

Larval habitat. Larvae were collected in a small stream running in dark forest; just below the waterfall, this stream represent a chain of pools bordered by rocks, among which the first pool (into which the waterfall falls) is large, and downstream pools are smaller; all larvae of P. (O.) niger   sp. n. were collected in a single pool, which is the 3rd from the waterfall; in spite of intensive collecting, in other places of this stream such larvae were not found.

Comparison. Larva of the new species P. (O.) niger   sp. n. differs from P. (O.) barnardi   sp. n. and P. (O.) cylindroculum   by the uniform brown coloration of abdominal terga, longer rows of denticles on claws and by the presence of lateral spines on abdominal segment IX only. Thin terminal portions of cerci lacking swimming setae and spines, in P. (O.) niger   sp. n. are usually longer than in other species ( Fig. 43 View FIGURES 43–48 ). Imago and subimago of P. (O.) niger   sp. n. differs from P. (O.) barnardi   sp. n. and P. (O.) cylindroculum   by the presence of 2 apical spines on middle and hind tarsi ( Fig. 77 View FIGURES 73–77 ). Winged stages of male and female differ from other species by more extensive and uniform brown hypodermal pigmentation of abdominal terga.


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