Waynokiops dentatogriphus, Hill, Matthew A., Pfeiffer, John & Jacobus, Luke M., 2010

Hill, Matthew A., Pfeiffer, John & Jacobus, Luke M., 2010, A new genus and new species of Baetidae (Ephemeroptera) from lakes and reservoirs in eastern North America, Zootaxa 2481, pp. 61-68 : 62-67

Waynokiops dentatogriphus , new species

( Figs. 1–13 )

Type material. HOLOTYPE: nymph (preserved in ethanol), ARKANSAS, Johnson County, Horsehead Lake, 26-VIII-2007 [ USNM]. PARATYPES: five nymphs, same data as holotype [ INHS].

Other material examined. U.S.A.: INDIANA, Bartholomew County: Tipton Lakes, 13-VIII-2007, one nymph [ PERC]; Steuben County: Lake James, 24-VII-2007, one nymph [ PERC]. OHIO, Brown County: Lake Waynoka, 2-VIII-2007, three nymphs [ PERC, INHS]. VIRGINIA, Suffolk/Isle of Wight Counties: Burnt Mills Lake, 19-IX-2007, one nymph [ USNM]. KENTUCKY, Christian County: Pennyrile Lake, 17- VIII-2007, two nymphs [ INHS].

Description. Nymph (preserved in ethanol). Body length of final instar: 4.5 mm, excluding caudal filaments. Color: White with tiny, dark brown maculations scattered over dorsal surface.

Head ( Fig. 1 ) narrow, hypognathous, coronal suture acute. Eyes protuberant, protruding beyond outline of head in anterior view ( Fig.1 ). Antennae 2.5 times length of head. Pedicel and scape cylidrical, subequal in length. Labrum ( Fig. 2 ) with shallow median excavation on distal edge. Mandibles ( Figs. 3, 4 ) incisors cleft to base. Maxillae ( Fig. 5 ) with palp narrow, attenuate and two-segmented. Lacinia stout, pointed, with comb of thick setae on distal half of medial edge below apical tooth. Apical tooth of lacinia 0.4 times length of lacinia. Labium ( Fig. 6 ) with paraglossae slightly longer than glossae. Glossae convex laterally, medial margin straight in proximal half, concave distally, apex bluntly pointed. Paraglossae round at apex. Labial palp ( Fig. 7 ) segment 1 rectangular, as long as segments 2 and 3 combined, and with peg-like setae on lateral surface. Segment two glabrous and 0.5 times length of segment 1. Segment 3 distally explanate and truncate; lateral and distal margins densely setose; subequal in length to segment 2, with distal width 1.5 times proximal width; apicolateral corner with blunt, triangular tooth; tooth length subequal to width.

Pronotum ( Figs. 8, 9 ) width 3.5 times length, with two pairs of low mounds, one pair sublaterad of midline and one pair near lateral margins. Mesonotum ( Figs. 8, 9 ) roughly sculptured, with median, longitudinal ridge slightly projected in lateral aspect. Hind wingpads absent. Legs ( Fig. 10 ) with femur 5 times longer than wide; femur with ventral row of short, lanceolate setae and with sparse distribution of fine setae dorsally. Patellotibial region of mesothoracic leg as in Figure 13 . Tibia and tarsus subequal in length and width, each bearing ventral row of pectinate, lanceolate setae, and with sparse distribution of dorsal fine setae. Tarsal claw slightly curved, subequal in length to tarsus, with two rows of tiny denticles ( Fig. 11 ) restricted to proximal 0.25 length.

Abdomen dorsoventrally compressed. Segments 1–9 each with dark, transverse band on lateral margins (most apparent on later instars). Triangular, acute, posteriorly-directed lateral expansions present on segments 1–7 and parallel-sided lateral flanges present on segments 8–9 ( Fig. 8 ). Lateral processes on segment 7 with stout spinules on posterior margins. Lateral expansions of segments 8 and 9 with stout spinules on posterior half of lateral margins and on free posterior margins. Such stout spinules sometimes present on more anterior segments. Single, median, erect, posteriorly hooked spines present on terga 1–6, decreasing in relative development posteriorly ( Fig. 9 ). Broad, bilamellate gills ( Fig. 12 ) present on abdominal segments 1–7. Dorsal lamella of gills round, approximately half size of lower lamella. Lower lamella triangular, with broken, branched venation. Cerci and median filament ( Fig. 8 ) pale with numerous, narrow faint darker bands. Median filament with lateral setal fringes continuous throughout length. Cerci with medial setal fringe continuous throughout length. Caudal filaments subequal in length to each other, and to length of abdomen.

Adult. Unknown.

Etymology. The specific epithet is a combination of the Latin word dentatus, meaning toothed, and griphus, meaning riddle. This name is a reference to the prominent median protuberances on the abdominal terga, and to the puzzling morphology and phylogenetic position of the species. The gender is masculine.

Morphological variability. The stout spinules of the lateral and sometimes posterior margins of abdominal terga vary in the size and number per segment. The spinules are smaller and fewer in number on more anterior segments. One specimen ( U.S.A., Indiana, Bartholomew County) has such spinules present as far anteriorly as segment two; however, most specimens do not have them appear this far anteriorly. The spinules usually begin to appear around segment 6. Later instars have larger and more numerous spinules. Likewise, the single, median, erect, posteriorly hooked spines present on the abdominal terga vary in their relative development.

Diagnosis. The monotypic new genus is distinguishable from all other Baetidae by having the following combination of characters: somewhat truncate and expanded labial palp segment 3 ( Fig. 7 ), variously developed lateral spinules on the abdomen ( Gillies, 1990: Figs. 2, 3 ), laterally expanded abdominal segments ( Fig. 8 ) and medial armature on the abdominal terga ( Fig. 9 ).

We modify a recent and widely-used key to genera of North American mayfly nymphs ( Waltz & Burian, 2008) to accommodate Waynokiops , new genus, as follows, because an impasse is reached at couplet 24.

24 (23’). Median tubercles present on anterior abdominal terga..................................................................................... 24a 24’. No median tubercles on abdominal terga ............................................................................................................ 25 24a. Abdominal gills (or gill sockets) present on segments 1–5 only; gills extend ventrally from the pleura; South-

west, Texas, Utah ................................................................................................... Baetodes Needham & Murphy 24a’. Abdominal gills (or gill sockets) present on segments 1–7; gills held dorsally; Central and East .........................

.......................................................................................................................................... Waynokiops , new genus

Discussion. The new genus is part of the Cloeon Leach complex of genera. This possibly monophyletic group (reviewed in parts by Kluge & Novikova, 1992; Monaghan et al., 2005; Gattolliat et al., 2008; Ogden et al., 2009: Figs. 3, 6 ) is defined here to include those Baetidae that have nymphs with the following synapomorphies ( Kluge and Novikova, 1992): an at least somewhat truncate and expanded labial palp segment 3 (similar to Figure 7 ) and variously developed lateral spinules on the abdomen ( Gillies, 1990: Figs. 2, 3 ). These spinules sometimes are minute and restricted to only one or two segments. Caudal filaments with dark rings on about every fourth segment may be another synapomorphy of the Cloeon complex genus groups, but our few nymphs with intact caudal filaments were faded, and we could not evaluate the character with confidence. Worldwide, the Cloeon complex includes Waynokiops , new genus, Cloeon Leach , Centroptilum Eaton [= Neocloeon Traver ], Similicloeon Kluge & Novikova , Intercloeon Kluge & Novikova , Pseudocentroptilum Bogoescu , Procloeon Bengtsson , Pseudocentroptiloides Jacob [= Psammonella Glazaczow ] and Securiops Jacobus, McCafferty & Gattolliat. In North America, species of the Cloeon complex are classified into the genera Cloeon , Centroptilum , Procloeon , Pseudocentroptiloides and now, Waynokiops , new genus. Globally, the rank and application of these names varies among current Ephemeroptera specialists.

Our new genus has characteristics that Kluge & Novikova (1992) considered separately apomorphic for the genus groups Cloeon and Centroptilum , namely the expanded gills, mandibles with incisors cleft to bases and shapes of labial palps. Thus, we advocate critical evaluation of these characters with regards to their use and interpretation in phylogenetic inference. We also call attention to the apical projection on labial palp segment 3 and its similarity to a potentially a homologous structure in Securiops (Jacobus et al., 2006: Figs. 6 , 14). Notably, Securiops also has mandibles with deeply cleft mandibular incisors (Jacobus et al., 2006: Figs. 8–11 ).

Our new genus demonstrates autapomorphies, including the expanded abdominal segments 1–7 and the dorsal abdominal armature. Dorsal abdominal armature on a baetid nymph from lentic habitats is of particular interest, because thusfar, such armature has been found only within genera whose nymphs are associated with lotic habitats. These genera include Acentrella Bengtsson , Acanthiops Waltz & McCafferty , Afrobaetodes Demoulin , Baetiella Ueno , Baetodes Needham & Murphy , Cheleocloeon Wuillot & Gillies , Dicentroptilum Wuillot & Gillies , Echinobaetis Mol , Gratia Thomas , Jubabaetis Muller-Liebenau , Papuanatula Lugo-Ortiz & McCafferty , Tanzaniops McCafferty & Barber-James and Thraulobaetodes Elouard and Hideux ( Thomas, 1992; Waltz & McCafferty, 1987; Wuillot & Gllies, 1993; Boonsoong et al., 2002; McCafferty, 2003; McCafferty & Barber-James, 2005; Jacobus & McCafferty, 2006).

Figures

FIGURES 1 – 6. Waynokiops dentatogriphus, new genus, new species. 1. Head, anterior view, cleared and with mouthparts removed. 2. Labrum. 3. Right (planate) mandible. 4. Left (angulate) mandible. 5. Maxilla. 6. Labium.

FIGURES 7 – 9. Waynokiops dentatogriphus, new genus, new species. 7. Labial palp. 8. Dorsal view, whole. 9. Lateral view, whole.

FIGURES 10 – 13. Waynokiops dentatogriphus, new genus, new species. 10. Mesothoracic leg. 11. Tarsal claw; note double row of denticles restricted to proximal quarter of claw. 12. Gill VI. 13. Mesothoracic leg, patellotibial region.