Securiops, : Kluge, 2020

Kluge, Nikita J., 2023, Redescription of the subgenus Securiops Jacobus, McCafferty & Gattolliat 2006 (Ephemeroptera, Baetidae, Procloeon Bengtsson 1915), Zootaxa 5343 (3), pp. 243-272 : 246-249

Autapomorphies of Securiops

Larva is psammophylous, with adaptation for inhabitancy on sandy ground: legs are long and slender, with long claws ( Figs 28 , 67 , 112–114 ); mouth apparatus is modified, with labium greatly elongated; labium, maxillae and labrum having peculiar shape and setation:

Labrum ( Figs 31–33 , 100 ). Distal margin is nearly straight (neither sharply concave, nor sharply convex); median incision is wide and shallow; other distal margin is distinctly differentiated into paired submedian and paired lateral portions. The submedian portion has a groove bordered by a more prominent ventral flange and a less prominent dorsal flange; the regular row of marginal setae is attached inside this groove, between these two flanges. The lateral portion has no groove, and the regular row of marginal setae is attached openly on its distal margin. This structure of distal margin is different both from sharply concave in Pseudocentroptiloides , and from convex or straight with narrow median incision in other Procloeon /g1 and most other Baetidae ( Kluge 2016b: fig. 43; Kluge 2020a: fig. 16; Kluge 2020b: figs 49–50).

Maxillae ( Figs 36–38 ). The 2nd and the 3rd dentisetae are located at a distance from the 1st dentiseta, nearer to the proximal angle of biting margin; a few small setae are located between the 1st and the 2nd dentiseta. In other respects, maxilla retains plesiomorphic structure: apex is pointed, with 3 long, slender, arched maxillary canines; the 1st dentiseta has the same shape as the canines and is pressed to the canines. In other Procloeon s. l., the 2nd and the 3rd dentisetae are located close to the 1st dentiseta (e.g., Kluge 2016b: fig. 46; Kluge 2020a: fig. 17; Kluge 2020b: fig. 53).

Labium ( Figs 40–46 , 116–119 ). Paraglossae are greatly enlarged, three times longer than glossae; glossae and paraglossae are highly modified, with shape and setation different from the initial one (see below); labial palp is greatly widened apically (see below).

Glossa is short, with apex rounded. Ventral side of glossa proximally with a regular transverse row of very long and straight setae; being pressed on slide, these setae can be turned either proximally ( Fig. 43 ), or distally ( Fig. 41, 42, 45 ). Dorsal side of glossa distally with a regular, arched, transverse row of stout, pointed setae directed distally ( Fig. 46 ). Rounded apex of glossa is smooth, without setae. Glossa of Securiops differs from the initial one (see Kluge 2016a: 137–138 and figs 4–5; Kluge 2016b: figs 47–48), in that its apex is not pointed and lacks setae, but the marginal setal row is shifted to the dorsal side. Origin of the peculiar transverse ventral-proximal row of straight setae is unclear.

Paraglossae are very large and flattened, either oval ( Figs 40–43 ), or with inner margins angulate and diverging ( Fig. 116 ). Most surface of ventral and dorsal sides is smooth, lacking setae; lateral margin with a regular longitudinal row of long setae; median side with two regular longitudinal rows of larger setae and one longitudinal row of smaller setae dorsad of them. Paraglossa of Securiops differs from the initial one (see Kluge 2016a: 137–138 and figs 4–5; Kluge 2016b: figs 47–48), in that its apex is not pointed, and median margin is not evenly concave; possibly, two of the three regular setal rows along the median margin are homologous to the ventro-median and the dorso-median setal rows of the initial structure, and the setae on lateral margin correspond to the latero-apical setae of the initial structure.

Labial palp (with 3rd segment initially truncate) has 3rd+2nd segments greatly widened, triangular, with straight distal margin of the 3rd segment exceeding median margin of the 3rd+2nd segments; angle formed by lateral and distal margins is bent and stretched forming a small projection ( Fig. 44 , 116–117 ). Authors of the previous publications ( Gillies 1988, Lugo-Ortiz & McCafferty 1996, Kaltenbach et al. 2023) erroneously regarded labial palp of Securiops as 2-segmented taking the 2nd and the 3rd segments as one; actually, border between these segments is retained, as well as the muscle going from the 2nd segment to the base of 3rd segment ( Figs 40, 44 ).

Figures

FIGURES 25–30. Procloeon (Securiops) falcatum. 25–28, larval exuviae (with same magnification): 25, abdominal sterna; 26, abdominal terga; 27, half of pronotum and mesonotum; 28, fore leg; 29, exuviae of metanotum with hind protoptera, left metapleuron and 1st abdominal tergum, enlarged; 30, fore protopteron, to show correspondence between cuticular coloration and veins visible inside.

FIGURES 66–69. Larvae of Procloeon (Securiops) macafertiorum. 66–68, larval exuviae (with same magnification): 66, abdominal terga and sterna; 67, thoracic sterna, pleura, halves of metanotum with hind protoptera and right legs (arrows show hind protoptera); 68, half of pronotum and mesonotum; 69, last instar male larva.

FIGURES 106–115. Procloeon (Securiops) primasia, larval exuviae. 106–108, dark individual (female); 109–115, light individual (male); 106, 115, abdominal terga and sterna; 107, 110, half of pronotum and mesonotum; 108, 111, left thoracic pleura and half of metanotum; 109, part of head; 112–114, fore, middle and hind legs.

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 116–119. Procloeon (Securiops) primasia, exuviae of labium. 116, labium (ventral setae of glossae directed proximally); 117, 2nd and 3rd segments of labial palp; 118–119, glossae in ventral and dorsal views (ventral setae directed proximally). Abbreviations: pm1, pm2, pm3, 1st–3rd palpomeres; s.d, dorsal setae of glossae; s.v, ventral setae of glossa.