Procloeon, Bengtsson, 1915

Kluge, Nikita J., 2020, New subgenus Monilistylus subgen. n. and a new species Procloeon (Monilistylus) ornatipennis sp. n. (Ephemeroptera: Baetidae: Procloeon), Zootaxa 4742 (3), pp. 573-587 : 577

Procloeon /g1, or genus Procloeon Bengtsson 1915 s.l.

Branch «11»: Kluge & Novikova 1992: Fig. 11 ;

Procloeon /g1: Kluge 2012: 362;

genus Procloeon: Kluge 2016: 494 .

Type species: Cloeon bifidum Bengtsson 1912 .

Autapomorphy of Procloeon /g1. At distal part of larval cercus, each cercomere bears apically on its outer (lateral) side one large spine directed posteriorly; usually this spine is spindle-like thickened and its length exceeds length of cercomere ( Fig. 7 ).

Composition. The taxon Procloeon /g1 includes the plesiomorphon Procloeon /g2 (or subgenus Procloeon ), holophyletic subgenera Oculogaster Kluge 2016 , Pseudocentroptiloides Jacob (in Jacob & Glazaczow) 1987 , Securiops Jacobus, McCafferty & Gattolliat 2006 and Monilistylus subgen. n. Characters of these taxa are briefly given in the Table 1 .

Discussion. Among species of the taxon Procloeon s. l. and among its subordinated taxa Procloeon s. str, Pseudocentroptiloides and Securiops , some species have no hind wings, and some species have hind wings of the « Centroptilum - type », i.e. narrow, with two longitudinal veins and with hooked costal process. The same variability occurs within many baetid taxa, so recently presence/absence of hind wings is regarded to be purely a species-specific character. In the past, this character was used as a generic or subgeneric one. Particularly, some authors placed four-winged representatives of Procloeon s.str. in a separate genus or subgenus under the name « Cloeoptilum » (e.g., Kazlauskas 1972) or « Pseudocentroptilum » (e.g., Jacob 1991). The name « Cloeoptilum » remains to be unavailable, because type species have not been formally designated (Hubbard 1979). The name Pseudocentroptilum Bogoescu 1947 belongs to the monotypic taxon opposed to Procloeon s. l. as a whole, while Procloeon s. l. includes both twowinged and four-winged species ( Kluge & Novikova 1992; Kluge et al. 2014: 490). Both known species of the new subgenus Monilistylus have no hind wings.

Figures

FIGURES 9–25. Details of larvae. 9–23, Procloeon (Monilistylus) ornatipennis sp. n.: 9–15, tergalii I–VII (holotype); 16, labrum; 17, maxilla (dorsal view); 18, right mandible; 19, its kinetodontium rotated after pressure of slide; 20, left mandible; 21–23, its incisor, kinetodontium and prostheca rotated after pressure of slide. 24–25, Procloeon (Monilistylus) monilistylus, kinetodontium and prostheca rotated after pressure of slide.

FIGURES 1–8. Larval exuviae. 1–2, Procloeon (Monilistylus) monilistylus: 1, right half of pro- and mesonotum; 2, thoracic sterna, pleura, metanotum, abdominal sterna and terga. 3–8, Procloeon (Monilistylus) ornatipennis sp. n.: 3, right half of pro- and mesonotum; 4, head; 5, thoracic sterna, pleura, metanotum and two legs; 6, abdominal sterna and terga (with caudalii of holotype); 7–8, caudalii of holotype, enlarged.

Tables

TABLE. 1. Subordinated taxa of Procloeon/g1

	plesiomorphon Procloeon /g2	Oculogaster	Pseudocentroptiloides /g1 (incl. Psammonella )	Securiops	Monilistylus
Subgeneric characters:
Margin of labrum	with median incision	with median incision	V-shaped	straight	with median incision (Fig 16)
Mandibles	« Baetis -type»	« Baetis -type»	« Centroptilum -type»	« Centroptilum - type»	« Centroptilum - type» (Figs 18–25)
Maxilla	pointed	pointed	blunt with setal row	pointed	pointed (Fig. 17)
Glossa	pointed	pointed	blunt	blunt	pointed (Fig. 29)
Paraglossa	pointed	pointed	cylindric with dense apical setae	large oval	pointed (Fig. 29)
3rd segment of labial palp	widened	widened	greatly widened	greatly widened	widened (Fig 27)
Stout apical setae on femur	absent	2	absent	absent	absent (Figs 30–31)
Viviparity	–	+	–	–	–
Veins of pterostigma	several	1	several	several	several (Fig. 44)
Gonostyli	usual	usual	usual	usual	modified (Figs 41, 49–53)
Species-specific and individual characters:
Segments of maxillary palp	2–3	2–3	2–3	2	3 (Fig. 17)
Dorsal lamella of tergalii	+ / –	+	+ / –	+	– (Figs 9–15)
Hind wing	+ / –	–	+ / –	+ / –	–