Pedicelliops gen. nov., a new genus from West Africa with striking antennae (Ephemeroptera, Baetidae)

A new genus of Baetidae, Pedicelliops gen. nov., and a new species, P. capillifer sp. nov., are described from Guinea (West Africa) based on larvae. The new genus is characterized by having strongly enlarged pedicelli and very short flagella, a brush of dense, short setae between prostheca and mola of both mandibles, a small rectangular labrum, an apicolaterally pointed maxillary palp, a labial palp with a small distolateral protuberance and long setae ventrally on glossae and paraglossae. The femora of all legs are covered with numerous long, fine setae. The patellotibial suture is absent on the fore tibia and present on middle and hind tibiae. The claw is pointed with two rows of denticles. No spines are present on the posterior margins of the abdominal tergites. The imago remains unknown and the relationships with other African genera of Baetidae remains tentative. Despite being easily identifiable and of a fairly large size (body length ca. 5 mm), only two larvae were found in two highly sampled localities in West Africa.


Introduction
The family Baetidae has the highest species diversity among mayflies, comprising ca. 1,100 species in 114 genera (updated from Sartori and Brittain 2015;Jacobus et al. 2019), which is close to one third of all mayfly species worldwide. They have a cosmopolitan distribution excluding Antarctica and New Zealand. Investigations of the Abbreviations MZL Museum of Zoology Lausanne (Switzerland).
Diagnosis. Larva. This new genus is distinguished by the combination of the following characters: A) body elongate and slender, head clearly hypognathous (Figs 1, 2); B) base of antennae close to each other, with carina between them (Fig. 2d); C) antenna shorter than head length, with strong bilateral enlargement of pedicellus (Fig. 3a); D) labrum small and rectangular, distal margin with medial emargination and small, square process, dorsal surface with long, stout, simple setae, erratically distributed in distal part, not arranged in one arc (Fig. 4a); E) right mandible with a stick-like, apically denticulate prostheca and a brush of short, fine setae between prostheca and mola (Fig. 4b, c); F) left mandible with a robust prostheca, apically with a comb-shaped structure and with a brush of short, fine setae between prostheca and mola (Fig. 4d, e); G) hypopharynx with medial tuft of stout setae (Fig. 4g); H) maxillary palp 2-segmented (Fig. 4h); I) glossae basally broad, narrowing toward apex, slightly shorter than paraglossae, ventrolateral margin with a row of short, thin setae and a row of long, simple setae close to margin, apically with some robust, long, curved setae; stout paraglossae with convex outer margin and apex, ventrolateral margin with a row of long, simple setae; labial palps segment II with distolateral protuberance, directed distally, segment III conical (Fig. 4i,j); J) legs with many long, simple setae on margins and on both surfaces of femur, femoral patch absent on all legs, patellotibial suture absent on foreleg and present on middle and hind legs, claw robust and pointed, with two rows of denticles (Figs 5, 6); K) fore protoptera with a protuberance near inner margin (Fig. 2a, b); L) posterior margin of abdominal tergites I-VIII smooth without spines (Fig. 1a).
Imagines. Unknown. Etymology. Pedicelliops is an arbitrary combination of letters with allusion to the Latin pedicellus and the Greek iops. Pedicellus is with reference to the striking second segment of the antennae and iops with reference to the Baetidae which look and move like small fishes. The gender is masculine.
Description. Larva. (Figs 1-6). Body. Elongate and slender, head hypognathous (Figs 1, 2). Head. Antenna (Figs 3a,b,2c,d) shorter than head length with strong bilateral enlargement of pedicellus. Antennae bases in close proximity to each other, with small carina between them. Labrum (Fig. 4a). Small in comparison to other mouthparts, rectangular, wider than long; dorsal surface with long, stout, simple setae, erratically distributed in distal part, not arranged in one arc; ventrally with marginal row of setae composed of anterolateral long, simple setae and medial long, bifid setae.
Right mandible (Fig. 4b, c). Incisor and kinetodontium fused, both with welldeveloped denticles; inner margin of innermost denticle without a row of thin setae; prostheca stick-like, apically denticulate; margin between prostheca and mola with a brush of abundant, short, fine setae.   Left mandible (Fig. 4d-f ). Incisor and kinetodontium fused, both with well-developed denticles; prostheca robust, apically with comb-shaped structure; margin between prostheca and mola with a brush of abundant, short, fine setae.
Labium (Fig. 4i, j). Glossae basally broad, narrowing toward apex, slightly shorter than paraglossae; ventrolateral margin with a row of short, thin setae and a row of long, simple setae close to inner margin, apically with some robust, long, curved setae. Paraglossae with convex outer margin and apex; ventrolateral margin with a row of long, simple setae; apical margin with three rows of long, stout setae (Fig. 4j). Labial palps segment II with distolateral protuberance, segment III conical.
Thorax. Fore protoptera ( Fig. 2a, b). With a protuberance near inner margin. Hind protoptera. Absent. Foreleg (Figs 5a-c, 6a). Femur with many long, simple setae on dorsal and ventral margins and on both lateral surfaces; femoral patch absent; apex of femur with ventral lobe poorly developed; patellotibial suture absent; claw robust and pointed, with two divergent rows of denticles.
Middle and hind legs (Figs 5d-f, 6b, c). More slender than foreleg; femur with same setation as foreleg; femoral patch absent; anterior outer projection of femur apex directed towards the inner side of femur (Fig. 5d); patellotibial suture present; claw as in foreleg.
Caudal filaments (Fig. 1a, d). Inner margin of cerci with 2-18 long, thin setae per segment, increasing in number distally; paracercus bilaterally with 3 to more than 12 long, thin setae per segment, increasing in number distally. Paracercus not reduced, but broken.

Pedicelliops capillifer gen. et sp. nov.
http://zoobank.org/1A749009-4120-46F5-B79A-DEACAC30AF56 Figures 1-7 Diagnosis. Larva. As the genus is monospecific, it is difficult to propose a relevant specific diagnosis. We can presume specific differences in the shape of the labial and maxillary palps, and in the setation of the forefemur. Species with less derived characters (shape of the pedicel, reduction of the labrum) may also be expected. Etymology. With reference to the remarkable setation found ventrally on the glossae and paraglossae, and on the femora. Description. Larva. (Figs 1-6). Body length 5.2 mm. Colouration (Fig. 1a-d). Colouration strongly altered due to long term storage of the larvae in alcohol, with the cuticle becoming transparent. Head, thorax and abdomen dorsally brown, fore protoptera ecru. Head, thorax and abdomen light brown ventrally. Legs and caudalii light brown.
Labrum (Fig. 4a). Length 0.6× maximum width. Distal margin with medial emargination and a small, square process. Dorsal surface with long, stout, simple setae, erratically distributed in distal part, not arranged in one arc. Ventrally with marginal row of setae composed of anterolateral long, simple setae and medial long, bifid setae. Ventral surface with ca. three short, spine-like setae near lateral margin.
Right mandible (Fig. 4b, c). Incisor with four denticles; kinetodontium with three denticles. Margin between prostheca and mola straight; with setae along whole margin from prostheca to mola, shorter than 1/5 of prostheca. Tuft of setae present at apex of mola.
Left mandible (Fig. 4d-f ). Incisor with five denticles; kinetodontium with three denticles. Margin between prostheca and mola straight; with setae along whole margin, shorter than 1/5 of prostheca, and a minute denticle toward subtriangular process. Subtriangular process long and slender, above level of area between prostheca and mola. Tuft of setae present at apex of mola.
Both mandibles with lateral margins convex. Basal half laterally with small, spatulate setae.
Maxilla (Fig. 4h). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and two short, simple setae. Maxillary palp ca. 1.3× as long as length of galea-lacinia; palp segment II 1.3× length of segment I; segment I widening in distal part; short, fine, simple setae scattered over distal part of surface of segment II; segment I laterally with short, robust setae; apex of segment II laterally pointed.
Labium (Fig. 4i, j). Inner margin of glossa with a row of short, fine, simple setae; ventral surface with a row of long, fine, simple setae close to margin; apex with six long, robust setae, curved toward inner side, and two shorter, spine-like setae; outer margin bare. Paraglossa with outer margin and apex convex and inner margin concave, slightly curved inward; ventrally with three rows of long, robust setae in apical area, four short, fine, simple setae in anteromedial area and a row of four long, simple setae on margin;  dorsally with a row of six long, spine-like setae near inner margin. Labial palp with segment I 0.9× length of segments II and III combined. Segment I with few short, fine, simple setae ventrally. Segment II with slender, distolateral protuberance, directed distad; distomedial protuberance 0.3× width of base of segment III; ventral surface with short, fine, simple setae; dorsally without spine-like setae near outer margin. Segment III conical; length 0.8× width; ventrally covered with short, spine-like setae and short, fine, simple setae.
Thorax. Fore protoptera (Fig. 2a, b). With a protuberance near inner margin. Hind protoptera. Absent. Foreleg (Figs 5a-c, 6a). Ratio of foreleg segments 1.4: 1.0: 0.8: 0.4. Femur. Broad, length ca. 2× maximum width. With many long, simple setae on dorsal and ventral margins as well as on anterior and posterior surface; length of setae mostly ca. 0.6× maximum width of femur; femoral patch absent. Tibia. Dorsal margin bare; with a row of medium, spine-like setae along ventral margin; one medium, spine-like seta at distomedial margin. Patellotibial suture absent. Tarsus. Dorsal and ventral margins bare, with short to medium, spine-like setae scattered over surface. Claw robust and distally pointed, with two divergent rows of denticles; denticles with different sizes, two apical denticles clearly larger than other denticles; subapical setae absent (Fig. 2b).
Middle and hind leg (Figs 5d, e, 6b, c). Ratio of middle and hind leg segments 1.2: 1.0: 0.6: 0.3. Femur. Length ca. 3× maximum width. With same setation as foreleg; femoral patch absent. Tibia. Dorsal margin bare. Ventral margin margin with a row of short, spine-like setae. Patellotibial suture present on basal ½ area. Tarsus. Dorsal margin bare. Ventral margin with a row of short, spine-like setae. Claw as foreleg.  (Fig. 3c, d). Seven pairs of gills on segments I-VII. Margin undulated, with short, stout, curved setae. Tracheae partly extending from main trunk to inner and outer margins. Gill I as long as the length of segments II and 2/3 of III combined. Gills II-VII unknown.

Discussion
Pedicelliops gen. nov. clearly belongs to the family Baetidae based on the long, slender, pisciform body shape; the labrum with distinctly expressed median incision; the shape of the right and left prostheca; the fused incisor and kinetodontium of both mandibles; the shape of the glossae (basally widened, most part narrow); and the anterior outer projection of the femur apex, which is directed toward the inner side of the femur (middle and hind legs only, in fore femur not like this; Fig. 5a, d) (Wang and McCafferty 1996;Kluge 2004). The new genus can be assigned to the Protopatellata according to the rank free system of Kluge (Kluge 1997;Kluge and Novikova 2011), based on the absence of a patellotibial suture in the foreleg and its presence in middle and hind legs of the larva. The following characters differentiate Pedicelliops gen. nov. from all other genera of Protopatellata: short antennae with bilaterally strongly enlarged pedicelli (Fig. 3a); small labrum in comparison to other mouthparts (Fig. 4); labium with long and short setae on ventral surface of glossae and paraglossae and the labial palps with a distolateral protuberance (Fig. 4i, j), directed distad; and femora of all legs with long setation on dorsal and ventral margins as well as on anterior and posterior surfaces (Fig. 5a, b). From the illustrations, it appears that Micksiops bicaudatus (Gillies, 1990) also has glossae and paraglossae with short and long setae on ventral side (Gillies 1990: fig. 91), but labrum, mandibles, maxillae and legs are dissimilar to Pedicelliops gen. nov. Bugilliesia sudanensis (Ulmer, 1916), B. grisea (Gillies, 1990) and B. guineensis (Gillies, 1990) similarly have long setae ventrolaterally on the paraglossae, the labial palp segments II have a distolateral protuberance, both mandibles have a brush of setae between prostheca and mola, and incisors and kinetodontium of both mandibles are fused. However, labrum, maxillary palps and legs are dissimilar (Gillies 1990: figs 67-70, 74-81, 84 -Ortiz, 1998. Most genera of this complex have the right incisor and kinetodontium only partially fused and the claws have two rows of denticles increasing in size progressively. Protopatellata are mainly distributed in the Afrotropics, with the exception of Indocloeon Müller-Liebenau, 1982, with a large repartition in the Oriental realm (Kluge 2012a;Kaltenbach and Gattolliat 2017;Kluge and Chanaporn 2020). As seen in Pedicelliops gen. nov., Indocloeon also generally presents labial palps with a distolateral protuberance, setae between prostheca and mola, and claws with two rows of denticles, with the apical denticles strongly enlarged. However, Indocloeon does not present any of the peculiar adaptations of Pedicelliops gen. nov. as listed above. The genus Varipes Lugo-Ortiz & McCafferty, 1998 from South America also has femora and trochanters with long, dense setae (including transverse rows of setae, which are absent in Pedicelliops gen. nov.), claws with two rows of denticles and labial palp segments II with a distolateral protuberance. However, as the two genera differ in many other aspects and as Varipes is not part of the Protopatellata (Dominguez et al. 2006), the similarities are most certainly due to convergence.
Pedicelliops capillifer gen. et sp. nov. has protuberances close to the inner margin of the fore protoptera (Fig. 2a, b). Comparable structures are described from a few other Baetidae as well: Monocentroptilum badium (Kopelke, 1980) from East Africa has a pair of small protuberances on the mesonotum (Kluge 2018: fig. 1), Asiobaetodes eloi Gattolliat, 2012 from Borneo has paired protuberances on the pronotum and on the base of the inner margin of the fore protoptera (Gattolliat 2012: fig. 17) and the Neotropical Paracloeodes binodulus Lugo-Ortiz & McCafferty, 1996 has small protuberances between the fore protoptera (Dominguez et al. 2006: fig. 55O).
The description of Pedicelliops gen. nov. is based on only two larvae, which were collected over three decades ago. Remarkably, these larvae were found in the two most regularly sampled localities by the ORSTOM team in West Africa (around fifty visits over the years 1984 to 1987). Most of the material from this region was studied by one of the authors (Gattolliat 2006), and because of its large size and its ease of recognition, we can assume that no additional material was overlooked. It could mean that this species is extremely rare, or it occurs in microhabitats which were not or only rarely sampled and the two specimens were collected by chance. Alternatively, the species may be prone to deteriorating environmental conditions over the last decades.
The number of localities and different habitats sampled in West Africa are limited and there are still vast regions where no collection activities have occurred. It would be prudent to assume that the number of genera and species of Baetidae will continue to increase with further field work and collections in these regions.