Susua sigiensis ( Gillies 2001 )

Kluge, Nikita J., Gattolliat, Jean-Luc, Salles, Frederico F. & Novikova, Eugenia A., 2018, Revision of the Afrotropical genus Susua Lugo-Ortiz & McCafferty 1998 (Ephemeroptera: Baetidae: Protopatellata), Zootaxa 4434 (1), pp. 1-28 : 5-17

Susua sigiensis ( Gillies 2001)

( Figs 1–61 )

Dabulamanzia sp. n.: Gillies 1999: 53.

Cheleocloeon sigiensis Gillies 2001: 23 (♂ and ♀ imago, larva).

Susua sigiensis: Kluge, Gattolliat & Salles 2017: 402 .

Material examined. Holotype ( NHM): TANZANIA, Upper Sigi R., below Ukunywi, Amani, 23.II. [19]91, B551: L-I ♂ (male imago in spirit, larval skin on slide QR code 010016901) . Paratypes ( NHM): the same locality and date, B552: L-I ♀ (female imago in spirit, forewing on slide QR code 0 10016902, larval skin on slide QR code 0100169001); B553: L-I ♂ (male imago in spirit, forewing and hind wing on slide QR code 0 10016903, larval skin on slide QR code 010016910); the same locality, 1.VII. [19]62, A 471-2 : 2 I ♂; 16/17.II. [19]63, A 653 : 1 I ♂. Nontype specimen ( NHM): Chemka, Amani, Tanganyika,8/ 9.XII. [19]62, A 584 : 1 I ♂. Other topotypes: TANZANIA, Tanga Province, Usambara Mountains, Amani , Upper Sigi River , 5°06'S, 38°38'E, 19.VIII–2.IX.2016, coll. N. Kluge & L. Sheyko: 1 L-S/I ♂ {number [XXXIX](2)}, 1 L-S ♂ {number [XXXIX](3)}, 1 L-S-I ♀ {number [XXXIX](5)}, 1 L-S ♀ {number [XXX](9)} , 12 larvae ( ZIN). Other localities: TANZANIA, Morogoro Province, Uluguru Mountains: Kinole , basin of River Ruvu , 6°54'S, 37°45'E, 27–30.VII.2017, coll. N. Kluge & L. Sheyko: 3L-S-I ♂ {numbers [V](11), [V](30), [VI](4)A}, 2 L-S ♂ {number [VI](4)A}, 2 L-S-I ♀ {numbers [V](8), [VI](4)A}, 1 L-S ♀ {number [V](30)} , 15 larvae ( ZIN); River Morogoro in Morogoro, 31.VII.2017, coll. N. Kluge & L. Sheyko: 1 L/S ♀ ( ZIN). Udzungwa Mountains, River Msosa (tributary of Great Ruaha), Msosa Camp (9 km S

Mbuyuni), 7°33'S / 36°32'E, 5–10.VIII.2017, coll. N. Kluge & L.Sheyko: 3 L-S-I♂ {numbers [VIII](9), [XI](7)}, 3 L-S♂ {numbers [X](11), [XII](5)B}, 1 L-S-I♀ {number [XII](5)B}, 2 L-S♀ {number [XII](5)B}, 12 larvae (ZIN).

Descriptions. Larva. CUTICULAR COLORATION. Head with brown and colorless areas; area between eyes unicolor. Pronotum and mesonotum with brown and colorless areas; fore protoptera darker in proximal half, lighter in distal half, with stripes darker than background along convex veins and stripes lighter than background along concave veins ( Figs 11 , 41 ). Metanotum brown with colorless areas; hind protoptera dark in proximal half, colorless in distal half ( Figs 14 ). Prothoracic pleura colorless; mesothoracis and metathoracic pleura often brown. Thoracic sterna colorless. Legs at most part colorless, with brown apex of femur ( Figs 13–15 ), sometimes with other areas colored by brown, especially on fore legs. Abdomen with constant coloration: terga I–II at most part colorless; terga III–VI brown with uniform paired blanks; terga VII–VIII either colorless, or light ocher with paired blanks as on previous terga; tergum IX at most part brown; tergum X colorless with brown anterior part ( Fig. 12 ). Abdominal sterna colorless. Cerci and paracercus proximally and apically colorless, in middle part diffusively colored by brown, paracercus lighter than cerci; each swimming seta brown proximally, colorless distally ( Fig. 10 ).

HYPODERMAL COLORATION. In immature larva not expressed; in last instar larva preparing to molt to subimago, abdominal terga with reddish marks as in imago.

STRUCTURE. Larval head and mouthparts as characterized above [see Crassabwa /g1 (1), (7)–(11) and diagnosis of Susua ]. In contrast to S. niandanensis , labium with mentum colorless, lacking contrasting sclerites ( Fig. 16 ); labial palp with 3rd segment blunt ( Fig. 5 ).

Head, pronotum and mesonotum (including anterior parts of fore protoptera) with numerous delicate (invisible in Canadian balsam), long, pointed scales, whose shape varies from narrow triangles ( Fig. 32 ) to seta-like. Posterior parts of fore protoptera with short, blunt scales ( Fig. 33 ). Besides this, pronotum and mesonotum with several pairs of compact bunches of more stout spatulate setae: one pair near posterior margin of pronotum; one pair near posterior margin of mesonotum between fore protoptera; 1–3 pairs along lines of fusion of mesonotum with fore protoptera ( Figs 28–31 , 41 ).

Mesonotum with high and short median ridge, steeply terminated posteriorly ( Fig. 41 ) (the same in subimago and imago of both sexes). Hind protoptera equally developed in both sexes ( Fig. 14 ). Legs as characterized above [see Crassabwa /g1 (2)–(4), (12)–(14)], relatively slender ( Figs 13–15 ).

Abdominal terga with numerous scales varying from wide, short, blunt, with wide sockets to narrow, long, pointed, with narrow sockets ( Figs 34–38 ). Posterior margin of postnotum and abdominal terga I–II without denticles, with 2–4 bunches of spatulate setae ( Figs 34–35 ); posterior margin of abdominal terga III–VII without denticles, with blunt scales of variable length, some of which situated sparsely and some form compact groups ( Fig. 36 ); posterior margin of terga VIII–IX with such scales irregularly alternating with sparse, pointed denticles ( Figs 37–38 ); on tergum IX row of denticles interrupted medially, behind submedian pair of setae ( Fig. 38 ); posterior margin of abdominal tergum X without denticles, with few small scales ( Fig. 39 ). Latero-posterior angles of abdominal terga V–X with several large pointed denticles ( Fig. 39 ). Abdominal sterna with short, blunt scales and short fine setae not forming rows; posterior margin of sterna either without denticles, or with very small sparse denticles ( Fig. 40 ). Paraprocts with pointed denticles ( Fig. 27 ). Each tergalius I–VII with long costal and anal ribs on costal and anal margins, with distal margin not bordered by rib, restricted portion of costal margin serratulate; tergalius I narrow, widest in distal part, bent backward, as long as tergalii of next pairs; tergalius II widened in middle part, with costal margin nearly straight and anal margin sharply convex; tergalii III–VI more symmetric; tergalius VII smallest, with costal margin sharply convex and anal margin nearly straight ( Figs 20–26 ). Cerci with small denticles on lateral sides of all segments; in distal half of cercus outer side with dense secondary swimming setae, not forming regular row ( Fig. 10 ).

RESPIRATORY MOVEMENTS. Absent. Living larva often keeps its tergalii perpendicular to body axis, that is characteristic for larvae whose tergalii are able for respiratory movements; shape of tergalii of Susua sigiensis is similar to that of Dabulamanzia and Cheleocloeon , whose tergalii are able for respiratory movements. Despite of this, larva of Susua sigiensis never makes respiratory movements by its tergalii and cannot live in container with stagnant water longer than several hours (in contrast to sympatric species of Dabulamanzia and Cheleocloeon , whose larvae can live in such condition during many days).

Subimago. CUTICULAR COLORATION. Head colorless. Pronotum with light brown and colorless areas. Mesonotum light brown, sutures at anterolateral part dark brown ( Fig. 51 ). Thoracic pleura and sterna at most part nearly colorless with brown microtrichia, certain sclerites brown ( Fig. 49 ). Legs nearly colorless with brown microtrichia. Abdominal terga and sterna very light brownish with brown microtrichia; terga with brownish sublateral markings. Cerci colorless with brown spines.

TEXTURE. On all legs of male and female all tarsomeres covered by pointed microlepides.

Imago, male ( Figs 50–51 ). Thorax brown with ocher, with equally colored dorsal, ventral and lateral sides. Mesonotum with high and short median ridge, steeply terminated posteriorly ( Fig. 51 ). Femur of fore leg ocher with brownish, other legs pale ocher. Tarsus of middle and hind leg with apical spine on 2nd tarsomere (primary 3rd tarsomere); spine on 1 st tarsomere (primary 1st+2nd tarsomeres) either present ( Figs 45–46 ), or diminished, or absent ( Figs 43–44 ). Fore wing with membrane and veins colorless; pterostigma with 3–7 simple oblique veins ( Fig. 50 ; Gillies 2001: Fig. 1 ). Hind wings narrow, with fore margin nearly straight and hind margin slightly convex, apex rounded, 2 longitudinal veins, hooked costal projection (as in female—Fig. 52; Gillies 2001: Fig. 2 ). Abdominal terga ocher with reddish markings: terga II–VIII with lateral markings; terga II–III and VI with median spot; terga IV–V and VII–VIII with less intensive median markings; tergum IX entirely reddish; tergum X ocher ( Fig. 50 ). Abdominal sterna ocher, lateral tracheal trunks and bases of sternal tracheae partly colored by brown. Cerci whitish, apex of each segment narrowly bordered by reddish-brown.

Gonostyli: 1 st segment with sharply projected apical-median angle, 2nd segment widened apically, 3rd segment elongate and clavate ( Figs 2, 4 , 54, 56 ; Gillies 2001: Fig. 3 ). Each gonovectis with apex sharply widened; proximally with projection serving as place of attachment of gonovectal muscle ( Figs 53, 54, 56 ). Penial bridge medially with unpaired truncate projection of variable width and height ( Figs 2, 4 , 53, 54, 56 ). Unpaired styligeral muscle well-developed ( Fig. 56 ).

Imago, female ( Figs 42 , 47–48 ). Head dorsally ocher with brown markings; eyes widely separated. Thorax ocher with brown. Mesonotum with high and short median ridge, steeply terminated posteriorly ( Fig. 42 ). Leg coloration as in male. Tarsus of fore leg with one apical spine on 3rd tarsomere; middle and hind legs as in male. Coloration of abdominal terga as in male ( Fig. 47 ). Abdominal sterna ocher in median part, brownish laterally ( Fig. 48 ). Coloration of cerci as in male.

Eggs. Irregular oval, 0.15 mm length. Chorion with prominent ridges forming net; some of transverse ridges interrupted; each cell with small protuberance in middle ( Figs 58–61 ).

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

Distribution. Usambara, Uluguru and Udzungwa Mountains in Tanzania.

Discussion. Gillies (1999) preliminary reported this species as belonging to the genus Dabulamanzia . However, this species differs from Dabulamanzia by the shape of the labial palp, whose 2nd segment has an innerapical projection, and 3rd segment is narrow ( Fig. 5 ; Gillies 2001: Fig. 7 ), while in all species of Dabulamanzia 2nd segment of the labial palp has no inner-apical projection, and 3rd segment is widened.

Subsequently Gillies (2001) described this species as a representative of the genus Cheleocloeon . Corrected diagnosis of the genus Cheleocloeon , based on reliably associated imagoes, subimagoes and larvae of various species, is given in a previous paper ( Kluge 2016). Differences between the species sigiense [ Cheleocloeon ] and the genus Cheleocloeon , which proceed from the original description, are: (1) sigiense [Ch.] has no patella-tibial suture on larval fore leg, while Cheleocloeon belongs to Anteropatellata and all its species have patella-tibial suture equally developed on all larval legs; (2) sigiense [Ch.] has hind wings in female, while in Cheleocloeon hind wings can be present or absent in male, but never present in female; (3) in sigiense [Ch.] inner-apical projection of the second segment of labial palp is much smaller that in all species of Cheleocloeon ; (4) in sigiense [Ch.] last (third) segment of gonostylus is much longer than in all species of Cheleocloeon . Differences between sigiense [ Cheleocloeon ] and the genus Cheleocloeon , which proceed from examination of the new material described above, are: (5) sigiense [Ch.] has one subapical stout seta on each larval femur ( Fig. 18 ), while all species of Cheleocloeon have two subapical setae on each larval femur; (6) gonovectes of sigiense [Ch.] have widened apices ( Figs 53, 54, 56 ), while all species of Cheleocloeon have uniform structure of gonovectes with apices hooked and pointed.

Figures

FIGURES 1–4. Holotype of Susua sigiensis: 1, dorsal view; 2–3, genitalia; 4, larval exuviae.

FIGURES 5–9. Larva of Susua sigiensis. 5, labium (at left ventral view with muscles of glossa, paraglossa and palp shown by interrupted lines; at right dorsal view); 6, labrum (dorsal view); 7, apex of left maxilla; 8–9, biting edges of left and right mandibles. Abbreviations: ds1, ds2, ds3, dentisetae.

FIGURES 10–16. Exuviae of last instar larvae of Susua sigiensis. 10, caudalii; 11, right half of pronotum and mesonotum; 12, abdominal sterna, terga and caudalii; 13, fore leg; 14, middle leg with meso- and metathoracic pleura, half of metanotum and hind protopteron; 15, hind leg; 16, labium. Abbreviations: I–X, abdominal segments I–X; ppt, hind protopteron. Black triangle shows point where patella-tibial suture crosses inner margin.

FIGURES 17–27. Larva of Susua sigiensis. 17, base of tibia of fore leg, anterior view (setae on posterior side shown by interrupted lines); 18, apex of femur and base of tibia of middle leg, anterior view (setae on posterior side shown by interrupted lines); 19, claw; 20–26, tergalii I–VII; 27, paraproct.

FIGURES 28–33. Exuviae of left half of pronotum and mesonotum of last instar larva of Susua sigiensis. 28, general view; 29–31, bunches of spatulate setae on places shown by arrows; 32, scales on pronotum; 33, scales on posterior part of fore protopteron.

FIGURES 34–40. Exuviae of abdomen of last instar larva of Susua sigiensis. 34, tergum I; 35, tergum II; 36, tergum V; 37, tergum VIII; 38, tergum IX (black triangle shows midline); 39, tergum X; 40, sternum VII.

FIGURES 41–46. Susua sigiensis. 41, anterior part of larva; 42, anterior part of female imago; 43–44, hind leg of imago and its subimaginal exuviae; 45–46, the same of another specimen. Abbreviations: R, unpaired median ridge on mesonotum; S, paired bunches of spatulate setae on pronotum and mesonotum.

FIGURES 47–51. Susua sigiensis. 47–48, female imago, dorsal and ventral view; 49, subimaginal exuviae of left pleuron; 50, male imago; 51, male imago with subimaginal exuviae.

FIGURES 52–57. Susua sigiensis. 52, hind wing; 53, penis, ventral view; 54–55, genitals of male imago and its subimaginal exuviae, ventral view; 56, genitals of another specimen (penis dotted, its hidden parts shown by interrupted lines; median styligeral muscle, gonovectal muscles and right gonostylar muscle shown by interrupted lines; areas of anterior attachment of median paraproctal muscles shown by dotted lines); 57, subimaginal genitals developing under larval cuticle. Abbreviations: gs1, gs2, gs3, 1st–3rd segments of gonostylus; usg, unistyliger.

FIGURES 58–61. Eggs of Susua sigiensis.