Demoulinia crassi (Demoulin 1971)

Kluge, Nikita J., 2020, Demoulinia Gillies 1990 and two unnamed genera of the plesiomorphon Protopatellata (Ephemeroptera, Baetidae) from South Africa, Zootaxa 4820 (3), pp. 438-464 : 441-444

Demoulinia crassi (Demoulin 1971)

( Figs 1–5 , 8–23 , 26–37 , 39–43 , 45–56 , 68–71 )

? Cloeon aeneum Barnard 1932: 216 (♀ imago).

? Cloeon chaplini Barnard 1932: 216 (♂ and ♀ imago).

Centroptilum pulchrum Crass 1947: 88 (♂ imago, subimago, larva); Harrison & Agnew 1962: 283; Chutter 1963, 1970: 474, 475, 491.

Centroptilum crassi Demoulin 1970: 43 .

Demoulinia crassi: Gillies 1990: 125 ; Wuillot & Gillies 1993: 217 (labium).

Material examined. SOUTH AFRICA, Western Cape Province: Cape Winelands District, Jonkershoek Valley, Eerste River upstream Stellenbosch , Swiss Club (5 km SE Stellenbosch), 33°57′30′′S, 18°55′E, 18–22.I and 812.II.2019, coll. N. Kluge & L. Sheyko: 3 L-S-I ♂ , 7 L-S-I ♀, 27 larvae; Garden Route District, Grobbelaars River near mouth of Klein-leroux River (18 km N Oudshoorn), 33°25′S 22°16′E, 29.I.2019, coll. N. Kluge & L. Sheyko: 1 larva ; Garden Route District, Lodge «Wild Spirit», small tributary of Bobbejaans River 5 km NW Nature’s Valley, 33°57′S 23°31′30′′E, 3–5.II.2019, coll. N. Kluge & L. Sheyko: 1 larva .

Descriptions. Larva. Coloration composite, consisting of composite pattern of colorless and grayish-brown areas of cuticle (see below) and composite pattern of ocher and reddish-brown areas of hypoderm visible through cuticle (see below) ( Fig. 1 ).

CUTICULAR COLORATION. Clypeus and adjacent part of frons colorless, most part of frons brown, cranium between eyes often with 2 pairs of brown parallelepiped maculae ( Fig. 1 ), other head areas varying from colorless to brown. Pronotum partly colorless, with characteristic brown spots ( Fig. 2 ). Mesonotum with composite pattern of lighter and darker brownish areas; cuticle of fore protoptera varying from colorless to light brown, with darker brown stripes along veins expressed mostly in anal area ( Fig. 2 ). Legs mostly colorless, with brown band on distal part of femur, sometimes also on proximal part of tibia ( Fig. 32 ). Abdomen ( Fig. 3 ) with composite color pattern including pair of submedian ocellate maculae on each tergum II–IX; each ocellate macula consists of brown sigilla (roundish on anterior terga, elongate on middle terga and divided into elongate anterior medio-anterior and dot-like medio-posterior sigilla on posterior terga) surrounded by colorless area. Cuticle of terga II, III and/or VII often more or less darker than others. Caudalii colorless, with brown band on distal party and brown tips; each primary swimming seta of cercus and paracercus dark brown proximally, colorless distally ( Fig. 42 ).

HYPODERMAL COLORATION. Abdomen dorsally with pair of contrasting brown transverse stripes on each intersegmental membrane. Each abdominal tergum with brown coloration postero-laterally; this coloration most intensive on terga IV, VI and VIII (which alternate with terga having most intensive cuticular coloration) and on median part of tergum V ( Fig. 4 ).

SHAPE AND SETATION. Head, thorax and legs as characterized above [see Demoulinia (2)–(15)].

Claws of all legs very long and slender, proximal ¼ somewhat thicker; ventral side with longitudinal groove from base to tip; 2 rows of minute denticles on thicker proximal part by sides of groove ( Fig. 35–36 ), occasionally larger denticles more distally ( Fig. 37 ); slender distal part with fine longitudinal striation outside of groove, without oblique striation.

All abdominal terga I–X with regular row of unequal pointed denticles on posterior margin ( Figs 39, 41 ); no median interruption on tergum IX. Abdominal sterna I–IV with posterior margin smooth, sternum V with few point-ed denticles on posterior margin, sterna VI–IX with regular row of pointed denticles on posterior margin. Terga and sterna with pyriform or cordate scales in opercula-bearing sockets and long simple (non-bifurcate) setae, arranged evenly and irregularly, not forming rows on sterna ( Figs 39–40 ). Sublateral pair of bifurcate setae on terga VI–VII ( Fig. 39 ). Paraproct with median margin partly concave, posteriorly stretched into short projection with denticles directed perpendicular to its margin (i.e., not inclined caudally); posterior margin of cercotractor smooth, lacking denticles ( Fig. 43 ).

Tergalii I–VI widest proximally, with anal margin convex; tergalii I–II without ribs; tergalii III–VI with costal rib not reaching tergalius apex; tergalius VII widest near middle, with costal margin convex, with costal rib reaching middle ( Figs 5 , 45–51 ).

Caudalii with long primary swimming setae, without secondary swimming setae [see (4)]; posterior margins of segments with pointed denticles of various size, larger on each 4th or each 2nd segment ( Fig. 42 ).

RESPIRATORY MOVEMENTS. Tergalii able to make rhythmic respiratory movements.

Subimago. CUTICULAR COLORATION. Head and prothorax nearly colorless, with microtrichia brownish. Mesonotum at most part nearly colorless, with certain sutures brown ( Fig. 54 ). Metanotum and thoracic pleura and sterna at generally nearly colorless with certain sclerites brown ( Fig. 56 ). Abdominal terga with very light brownish and colorless areas ( Fig. 55 ); sterna nearly colorless. Cerci light brownish.

TEXTURE. In both sexes, on legs of all pairs, all tarsal segments covered with pointed microlepides; on each leg small basal part of first segment covered with microtrichia (as tibia and other leg segments) ( Figs 69–70 ).

Imago, male ( Figs 52–53 ). Head brown with ocher. Antennae ocher. Turbinate eyes with facetted surface red or orange, stem yellowish. Prothorax brown with ocher. Mesonotum with medioscutum brown, submedioscutum ocher, other parts mostly brown; mesothoracic pleura and sterna and metathorax brown with ocher. Wings colorless, veins pale. Legs of all pairs ocher, femur diffusively colored with brownish at middle and at apex. Middle and hind tarsus with proximal (initial 1st+2nd) tarsomere relatively long, with apical spines on 1st+2nd and on 3rd tarsomeres (as in Fig. 69 ). All abdominal terga I–X ocher with composite reddish-brown maculation, as hypodermal coloration of larva (see above); abdominal sterna ocher; lateral tracheal trunks partly black. Cerci light ocher with narrow brown ring on each articulation.

Genitalia ( Figs 59–61 ) mostly pale ocher. Gonostyli with sharply expressed boundary between 1st and 2nd segments, with base of 2nd segment somewhat inserted into 1st segment ( Fig. 63 ); 1st segment with prominent microlepides on median side; 2nd segment swollen basally and apically, with 3rd segment attached on median side of its apical swelling; 3rd segment small, hooked and pointed [see Demoulinia (1)]. Sterno-styligeral muscle narrow, unpaired, located medially, arising at some distance from anterior margin of sternum IX ( Fig. 63 ). Penis integral, with gonovectes tightly fused with penial bridge and not inserted into body ( Fig. 62 ), bilobed in apical view ( Fig. 64 ); penial bridge with very shallow median projection ( Fig. 62 ).

Imago, female ( Figs 67–68 ). Head ocher with brown spots. Pronotum ocher with or without brown spots. Mesonotum either entirely ocher, or with brownish stripe on medioscutum ( Fig. 67 ), or with entire medioscutum brown (similarly to male). Wings as in male (see above). Middle and hind legs as in male (see above); fore legs with apical spines on 2nd and on 3rd tarsomeres ( Fig. 70 ). Coloration of abdomen as in male (see above), but with black tracheae on terga.

Egg ( Fig. 71 ). Oval, 0.15 mm length; chorion with peculiar relief consisting of densely arranged angulate protuberances with flat surfaces.

Dimensions. Fore wing length (and body length) in male and female 5.5–6 mm (6.5–8 mm according to Crass 1947).

Senior species name. This species was described by Crass (1947) from Natal Province of South Africa under the name Centroptilum pulchrum ; this description was based on reliably associated imagines, subimagines and larvae. However, earlier Barnard (1932) described two species from the Western Cape Province of South Africa as Cloeon aeneum Barnard 1932 and Cloeon chaplini Barnard 1932 ; the first species was described from female imagines only, and the second from male and female imagines, but without description of male genitalia, so that the systematic position of both species is unclear. Both C. aeneum and C. chaplini were collected in Jonkershoek Valley near Stellenbosch ( Barnard 1932), the same place where we collected material of D. crassi described here. During our intensive collecting in 2019 in Eerste River (the single river running in this valley), we found the following species which could be attributed to Cloeon in the old sense (i.e. with single marginal intercalary per space and lacking hind wings): Demoulinia crassi ; Procloeon (Oculogaster) barnardi Kluge 2020b , Cloeon perkinsi Barnard 1932 , Cloeon virgiliae ( Barnard 1932 [ Austrocloeon ]), and Cheleocloeon excisum ( Barnard 1932 [ Centroptilum ]). Among them, female imagines of C. perkinsi , C. virgiliae and Ch. excisum were described in the same paper by Barnard (1932) and were distinguished by him from C. aeneum and C chaplini ; particularly, female imagines of C. perkinsi and C. virgiliae clearly differ by colored costal and subcostal areas of wings. Procloeon (Oculogaster) barnardi was described in the same paper under the wrong name « Austrocloeon africanum » and differs substantially from all other species under consideration by the presence of only one cross vein in the pterostigma ( Barnard 1932). Thus, we cannot exclude that the imagines described by Barnard (1932) under the names Cloeon aeneum and/or Cloeon chaplini , are conspecific with Demoulinia crassi .

Figures

FIGURE 71. Egg of Demoulinia crassi.

FIGURES 1–5. Larva of Demoulinia crassi. 1, Female larva of last instar; 2–3, exuviae of male larvae: 2, left half of prothorax and mesothorax; 3, abdomen; 4, abdomen of male subimago extracted from mature larva (to show hypodermal larval coloration); 5, tergalius III.

FIGURES 6–12. Labrum of Demoulinia spp., dorsal view. 6–7, D. insularis (holotype). 8–12, D. crassi.

FIGURES 13–20. Mandibles of Demoulinia crassi. 13, 16, 19, left mandible; 14, 17, 20, right mandible; 15, apex of right mandible, proximal view (inc, incisor; kd, kinetodontium; prs, prostheca).

FIGURES 21–25. Demoulinia spp. 21–23, D. crassi; 24–25, D. insularis (holotype); 21, 22, 24, maxilla (21, with focus on ventral side; 22, with focus on dorsal side; d1, d2, d3, dentisetae; p1, p2, p3, segments of maxillary palp); 23, 25, hypopharynx and superlingua.

FIGURES 26–31. Labium of Demoulinia crassi. 26, cross section of glossae and paraglossae; 27, labium and maxilla; 28–31, exuviae of glossae, paraglossae and labial palp: 28–29, with focus on ventral side; 30–31, with focus on dorsal side (gl:dl, dorsolateral row of stout setae on glossa; gl:m, median row of stout setae on glossa; gl:vm, setae corresponding to ventro-median row of glossa; pg:dm, dorso-median row of long setae on paraglossa; pg:la, latero-apical long setae of paraglossa; pg:vm, long setae corresponding to ventro-median row of paraglossa).

FIGURES 32–38. Larval legs of Demoulinia spp. 32–37, D. crassi: 32, exuviae of hind leg; 33, inner side of fore tarsus; 34, femoral-tibial of hind leg, focus on anterior side; 35–37, claws. 38, D. insularis (holotype), fragment of claw with subimaginal claws inside (arrow shows row of vestigial denticles on inner side).

FIGURES 39–44. Exuviae of larval abdomen of Demoulinia spp. 39–43, D. crassi: 39, lateral and posterior area of abdominal tergum VII; 40, anterior-lateral area of abdominal sternum VI; 41, caudalii; 42, fragment of cercus; 43, paraproct. 44, D. insularis (holotype), median margin of paraproct (scale bar refers to Figs 39, 40, 42, 43).

FIGURES 45–51. Demoulinia crassi, tergalii I–VII.

FIGURES 52–56. Demoulinia crassi. 52–53, male imago; 54–56, subimaginal exuviae: 54, left half of mesonotum; 55, abdomen; 56, fragment of pleuron with postsubalar sclerite.

FIGURES 67–70. Females of Demoulinia crassi. 67–68, female imago; 69–70, subimaginal exuviae of tibia and tarsus: 69, middle leg; 70, fore leg.

FIGURES 57–61. Male genitalia of Demoulinia spp. 57, D. insularis (paratype of D. assimilis), subimaginal gonostyli under larval cuticle. 58–61, D. crassi: 58, subimaginal gonostyli extracted from larva; 59, imaginal genitalia; 60–61, apex of imaginal gonostylus.

FIGURES 62–66. Male genitalia of Demoulinia crassi. 62, penis, ventral view (left muscles not shown); 63, genitalia, ventral view (penis dotted; left gonovectal muscle and right styligeral muscle not shown); 64, penis (dotted), posterior view (left muscle not shown); 65, subimaginal gonostyli crumpled under larval cuticle; 66, exuviae subimaginal of gonostyli (gd, gonoduct; gs1, gs2, gs3, segments of gonostylus; m.gv, gonovectal-sternal muscle; m.g-t, gonovectal-tergal muscle; m.pp, paces of attachment of muscles going to paraprocts; m.sg, sterno-styligeral muscle; usg, unistyliger).