Cloeonini, sensu Kluge, 2016

Kluge, Nikita J., 2023, Redescription of the subgenus Securiops Jacobus, McCafferty & Gattolliat 2006 (Ephemeroptera, Baetidae, Procloeon Bengtsson 1915), Zootaxa 5343 (3), pp. 243-272 : 244-246

Characters of Cloeonini , or Cloeon/fg1:

Mandibles. Both larval mandibles have dense setae between prostheca and mola ( Figs 34–35 , 98–99 ). The same in some other taxa.

Labial palp. The 3rd segment of labial palp is truncate, and the 2nd segment lacks apical-median projection, so that these two segments form an integral figure widened from base toward apex. At the same time, the border between these segments is retained, and the muscle going from the 2nd segment to the base of the 3rd segment is retained ( Fig. 40 ). An autapomorphy of Securiops is the great widening of this triangular formation (see below).

Larval patella-tibial suture. The proximal end of patella-tibial suture is bent distally and connected under acute angle with a row of long thin hairs (autapomorphy of Cloeon /fg1) ( Fig. 48 ).

Larval claw. In all Cloeon /fg1 larval claw is symmetric, slightly curved, either with 2 similar rows of denticles, or without denticles (plesiomorphy within Liberevenata). In all known species of Securiops claw is long and lacks denticles ( Fig. 50 ).

Lateral spines on larval abdomen. Lateral margins of abdominal segment IX and some previous segments bear spines (autapomorphy of Cloeon /fg1) ( Fig. 17 ; Kaltenbach et al. 2023: fig. 6a).

Scales on larval abdomen. Abdominal terga and some other body parts of larva bear translucent scales in wide, opened, semicircular sockets. The same in some other baetid taxa, in contrast to angulate and operculated sockets, which are probably initial for Turbanoculata ( Kluge 2004). In most species of Cloeon /fg1 such scales densely cover most part of surface of abdominal terga and sterna. Among Securiops , such scales are well-developed on abdominal terga III–X and sterna IV–IX in P. (S.) falcatum ( Figs 55–56 ); in P. (S.) mutadens such scales are sparse ( Fig. 103 ); in P. (S.) macafertiorum and P. (S.) primasia the scales are completely lost.

Tergalii. Tergalii have the costal rib, but lack the anal rib and can bear a second lobe, which represents an analproximal expansion curved dorsally (presence of such lobe is an autapomorphy of Cloeon /fg1). In various species of Cloeon /fg1, such second lobe is either present on all tergalii I–VII, or is absent on tergalius VII or some other tergalii of posterior pairs, or is absent on all tergalii. Tergalius VII usually lacks the second lobe and often has a peculiar form sharply different from other tergalii: its anal margin (lacking rib) is straight, and the costal margin (armed with the costal rib) is sharply convex ( Figs 7, 17, 24 ); being the last one, this tergalius is directed posteriorly and adjacent by its anal margin to the lateral margins of abdominal segments VIII–IX ( Fig. 17 ). Such shape of tergalius VII is especially characteristic for Procloeon /g1, but can be found in some other taxa, sometimes varying individually (e.g., Kluge & Novikova 1992: figs 7.7–8). Because of this difference between tergalius VII and other tergalii, some authors confuse its costal and anal margins and draw it in overturned position ( Gillies 1988: fig. 19; Gattolliat 2003: figs 19, 23; Jacobus et al. 2006: fig. 19; Kaltenbach et al. 2023: fig. 7b).

Mobility of tergalii. Tergalii are able to make intensive rhythmic respiratory movements (plesiomorphy).

Larval caudalii. Cerci and paracercus have dark rings on every 4th joining; segment preceding this joint bears a row of elongate denticles on its posterior margin ( Figs 71–72 , 124–125 ).

Subimaginal tarsus. In subimago all tarsomeres on legs of all pairs are covered with pointed microlepides, without blunt microlepides ( Fig. 70 ).

Pleuron of subimaginal mesothorax. Posterodorsal process of postsubalar sclerite is diminished, pointed, with concave antero-dorsal margin ( Fig. 130 );

Fore wing. Fore wing has no more than one marginal intercalary in each space (plesiomorphy within Liberevenata) ( Fig. 126 ).

Hind wing. Hind wing, if present, is narrow, with no more than two longitudinal veins, always with prominent, narrow, hooked costal process ( Fig. 83 ); in some species hind wings are completely absent, but no one species has hind wing lacking costal process. Among Securiops , hind wings of such structure are present in P. (S.) falcatum ( Fig. 64 ) and P. (S.) macafertiorum ( Fig. 83 ); in P. (S.) mutadens , P. (S.) primasia and other species hind wings are absent.

Gonostyli. The 2nd segment of gonostylus is thickened apically, and the 3rd segment is small and petiolate (autapomorphy of Cloeon /fg1) ( Figs 88, 90 , 137 ). Being developed under larval cuticle, subimaginal gonostyli are bent in the ́Cloeon - type » pose, that is their 2nd segments are directed laterally, and 3rd segments are directed medially (plesiomorphy within Turbanoculata) ( Fig. 60 ).

Penis. In male imago gonovectes are small and incapable for protraction; penial bridge is sclerotized and projected between unistyligers ( Figs 91 , 137–141 ).

Figures

FIGURES 31–39. Procloeon (Securiops) falcatum, larval mouthparts. 31, apex of labrum, ventral view; 32, labrum, dorsal view; 33, apex of labrum, enlarged; 34–35, left and right mandibles; 36, maxilla; 37–38, apex of maxilla with focus on ventral and dorsal sides; 39, hypopharynx with superlinguae.Abbreviations: can, maxillary canines; ds1, ds2, ds3, 1st–3rd dentisetae,

FIGURES 98–105. Procloeon (Securiops) mutadens. 98–99, left and right mandibles; 100, labrum; 101, maxilla; 102, larval cuticle of metanotum with vestige of hind protopteron; 103, abdominal tergum V; 104, abdominal sternum V; 105, caudalii. Abbreviation: sc, scales and scale sockets.

FIGURES 40–46. Procloeon (Securiops) falcatum, labium. 40, integral labium; 41–46, parts of exuviae: 41, glossae and paraglossae, ventral view; 42, half of labium of another individual (ventral setae of glossae directed distally); 43, the same individual, with ventral setae of glossae directed proximally; 44, distal segments of labial palp; 45–46, enlarged glossae in ventral and dorsal view (ventral setae directed distally). Abbreviations: m2-3, muscle going from 2nd palpomere to base of 3rd palpomere; pm1, pm2, pm3, 1st–3rd palpomeres; s.d, dorsal setae of glossae; s.v, ventral setae of glossa.

FIGURES 47–52. Procloeon (Securiops) falcatum, larva. 47, articulation of femur and tibia of fore leg, dorsal view; 48, the same, compressed to show junction of patella-tibial suture with row of fine hairs; 49, fragment of tarsus; 50, claw; 51, abdominal tergum X and margin of tergum IX; 52, abdominal tergum X and paraprocts.

FIGURES 1–24. Right tergalii of Securiops with dorsal lamella turned out. 1–7, Procloeon (Securiops) falcatum, tergalii I–VII; 8–17, two individuals of P. (S.) macafertiorum: 8–11, tergalii I–II and V–VII; 12–16, tergalii I–V; 17, the same individual, margins of abdominal segments VII–IX with tergalius VII in natural position; 18–24, P. (S.) primasia, tergalii I–VII.

FIGURES 53–58. Procloeon (Securiops) falcatum, exuviae of larval abdomen. 53–56, terga II, III, IV and IX; 57, sternum IV; 58, constant bifurcate seta on sublateral part of sternum VIII.

FIGURES 70–76. Procloeon (Securiops) macafertiorum. 70, subimaginal exuviae: apex of tibia and base of tarsus of fore leg of male; 71–76, larval exuviae: 71, caudalii; 72, fragment of cercus; 73, fragment of fore tarsus; 74, abdominal tergum IV; 75, abdominal sternum V; 76, abdominal tergum X, paraproct and margin of tergum IX.

FIGURES 120–125. Procloeon (Securiops) primasia, larval exuviae. 120, base of tibia of fore leg, with focus on dorsal side; 121, the same with focus on ventral side; 122, abdominal tergum V; 123, abdominal sternum VIII; 124, cercus and paracercus; 125, portion of cercus.

FIGURES 126–136. Procloeon (Securiops) primasia. 126–127, male imagines; 128, female imago; 129, subimaginal exuviae of half of mesonotum; 130, subimaginal exuviae of thoracic pleura; 131–133, fore leg of female imago; 134–136, its middle leg. Abbreviations: cx2, cx3, coxae of fore, middle and hind legs; lpnc, lateropostnotal crest; mtpl, pleurite of metathorax; pls, pleural suture; psa, postsubalar sclerite.

FIGURES 77–87. Procloeon (Securiops) macafertiorum. 77, 78, male imagines; 79, female imago; 80–87, parts of male imago and subimago reared from larva: 80–81, head and thorax; 82, abdomen; 83, hind wing; 84, subimaginal exuviae of thoracic pleura; 85, subimaginal exuviae of half of mesonotum; 86–87, fore and hind legs. Abbreviations: cx2, cx3, coxae of middle and hind legs; lpnc, lateropostnotal crest; mtpl, pleurite of metathorax; pls, pleural suture; psa, postsubalar sclerite.

FIGURES 59–65. Procloeon (Securiops) falcatum. 59–60, parts of male subimago extracted from larva: 59, abdomen; 60, genitalia; 61–64, young male subimago: 61, abdomen; 62, genitalia; 63, fore femur; 64, hind wing (partly crumpled); 65, genitalia of male imago (after Crass 1947). Abbreviations: gs1, gs2, gs3, 1st–3rd segments of gonostylus; pb, median projection of penial bridge; usg, unistyliger.

FIGURES 88–91. Procloeon (Securiops) macafertiorum. 88, genitalia of male imago reared from larva; 89, its subimaginal exuviae; 90, genitalia of another specimen, ventral view; 91, the same, with focus on penis.

FIGURES 137–142. Procloeon (Securiops) primasia. 137–141, genitalia of male imagines: 137, ventral view; 138, lateral view, right gonostylus and styliger removed; 139, lateral view of penis; 140, apex of penis with focus on its dorsal margin; 141, the same penis with focus on ventral side; 142, subimaginal exuviae of genitalia.