Nigrobaetis richardi, Kaltenbach & Mary & Gattolliat, 2021

Kaltenbach, Thomas, Mary, Nathalie & Gattolliat, Jean-Luc, 2021, The Baetidae (Ephemeroptera) of the Comoros and Mayotte, African Invertebrates 62 (2), pp. 427-463 : 427

6. Nigrobaetis richardi sp. nov.

Figures 10a , 11 , 12 , 13

Diagnosis.

Nymph. Following combination of characters: A) labrum on dorsal surface with ca. six stout, simple setae in distal half; B) right mandible with medium, stout setae between prostheca and mola; left mandible with minute denticles between prostheca and mola; C) labial palp segment II without distomedial protuberance; segment III slightly pentagonal; D) fore femur rather broad, length ca. 3 × maximum width; dorsal margin with 8-10 curved, lanceolate setae, apically pointed ; femoral patch absent; E) hind protoptera well developed; F) seven pairs of gills; G) paraproct with 5-7 marginal spines.

Description.

Nymph (Figs 10a , 11 , 12 ). Body length 3.3-3.8 mm. Cerci: broken. Paracercus: ca. ½ of body length. Antenna: broken.

Colouration (Fig. 10a ). Head, thorax and abdomen dorsally brown, tergites I, IV, VIII and IX light brown, ventrally light brown. Legs light brown, caudalii light brown.

Labrum (Fig. 11a ). Subrectangular, length 0.7 × maximum width. Distal margin with medial emargination and small process. Dorsally in proximal half with long, fine, simple setae scattered over surface; in distal half with one central, long, stout, simple seta, two longer and some shorter stout, simple setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid setae; ventral surface with ca. five short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 11b, c ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles, inner margin of innermost denticle with row of thin setae. Prostheca stick-like, distolaterally denticulate. Margin between prostheca and mola straight, with medium, stout setae. Tuft of setae at apex of mola present.

Left mandible (Fig. 11d, e ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with minute denticles. Subtriangular process long and slender, above level of area between prostheca and mola. Tuft of setae at apex of mola absent.

Both mandibles with lateral margins almost straight. Basal half with fine, simple setae scattered over dorsal surface.

Hypopharynx and superlinguae (Fig. 11f ). Lingua slightly longer than superlinguae. Lingua longer than broad; medial tuft of stout setae absent; distal half laterally slightly expanded. Superlinguae distally straight; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 11g ). Galea-lacinia ventrally with two simple, apical setae under canines. Inner dorsal row of setae with three denti-setae, distal denti-seta tooth-like, middle and proximal denti-setae slender, bifid and pectinate. Medially with one spine-like seta and four long, simple setae. Maxillary palp longer than length of galea-lacinia; 2-segmented; palp segment II 1.2 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment slightly pointed.

Labium (Fig. 11h, i ). Glossa basally broad, narrowing toward apex; as long as paraglossa; inner margin with seven spine-like setae; apex with two long, robust setae and one short, robust, pectinate seta; outer margin with six spine-like setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust setae in apical area, two short, simple setae in anteromedial area and one short, simple seta in posterolateral area; dorsally with row of three long, spine-like, simple setae near inner margin. Labial palp with segment I approximately as long as length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without distomedial protuberance; ventral surface with short, fine, simple setae; dorsally with four spine-like setae. Segment III slightly pentagonal; length 1.1 × maximum width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 12g ) well developed.

Foreleg (Fig. 12a-c ). Ratio of foreleg segments 1.3:1.0:0.6:0.2. Femur. Length ca. 3 × maximum width. Dorsal margin with 8-10 curved, lanceolate setae, apically pointed. Apex rounded, with pair of spine-like setae and fine, simple setae. Stout, lanceolate setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin with row of scarce, fine simple setae. Ventral margin with row of scarce, short, curved, spine-like setae, on apex some longer, partly pectinate setae. Anterior surface scattered with short, stout, lanceolate setae. Patellotibial suture present on basal 2/3 area. Tarsus. Dorsal margin with row of scarce, fine, simple setae. Ventral margin with row of curved, spine-like setae, partly pectinate. Claw with one row of 12 or 13 denticles; distally pointed; with ca. three stripes; subapical setae absent.

Middle and hind legs. As foreleg, but tibia dorsally with row of spine-like setae.

Terga (Fig. 12d ). Surface scattered with U-shaped scale bases. Posterior margin of terga I-III without spines; posterior margin of terga IV and V partly with some rudimentary, triangular spines; posterior margin of terga VI-IX with medial, triangular spines, longer than wide.

Gills (Fig. 12e, h ). Present on segments I-VII. Margin with small denticles intercalating short, fine simple setae. Tracheae only partly extending to inner and outer margins. Gill I as long as 2/3 of segment II; gill IV as long as length of segments V and 1/3 VI combined; gill VII as long as length of segments VIII and 2/3 IX combined.

Paraproct (Fig. 12f ). Distally not expanded, with 5-7 marginal spines. Surface scattered with U-shaped scale bases and micropores. Cercotractor with small, marginal spines.

Etymology.

Dedicated to the late entomologist Barton A. Richard (formerly Florida A&M University, Tallahassee), who participated in an early phase of this project (2004-2007).

Distribution

(Fig. 13 ). Comoros (Anjouan).

Biological aspects.

The specimens were collected at altitudes of 210 m and 600 m, together with L. glaucus , L. vinosus and P. freitagae . The characteristics and environmental conditions of the sampling sites in the Comoros (Anjouan, Riv. Tatinga) are described in Starmühlner (1979: pp. 652, 655): river width 3-10 m, depth 5-50 cm, water temperature 22 °C-24.5 °C, bottom substrata consisted of basaltic rock, boulders, gravel and sand.

Type material.

Holotype. Comoros • nymph; Anjouan, Riv. Tatinga, upper course, near Dindri ; 600 m; 11.03.1974; leg. F. Starmühlner; on slide; GBIFCH00515655 ; MZL. Paratypes. Comoros • 3 nymphs; Anjouan, Riv. Tatinga , lower course, by the bridge; 210 m; 22.03.1974; leg. F. Starmühlner; 2 on slides; GBIFCH00592759 , GBIFCH00592715 , GBIFCH00592716 ; MZL, 1 in alcohol; GBIFCH00515656 ; FAMU.

Figures

Figure 10. Nymphs, habitus: a Nigrobaetis richardi sp. nov. b Potamocloeon (A.) freitagae.

Figure 11. Nigrobaetis richardi sp. nov., nymph morphology: a labrum b right mandible c right prostheca d left mandible e left prostheca f hypopharynx and superlinguae g maxilla h labium i apex of paraglossa. Scale bar: 0.1 mm.

Figure 12. Nigrobaetis richardi sp. nov., nymph morphology: a foreleg b seta at dorsal margin of femur c fore claw d tergum IV e gill IV f paraproct g metanotum (left side), with hind protopteron (mature nymph) h gills I, II, III, IV (top to down). Scale bars: 0.1 mm.

Figure 13. Distribution of Nigrobaetis richardi sp. nov., Potamocloeon (A.) freitagae and Procloeon (O.) cylindroculum in the Comoros Archipelago.