Procloeon ( Psammonella ) mekongiense, Kluge, 2025

Procloeon ( Psammonella) mekongiense sp. nov.

( Figs 39–45 View FIGURES 32–59 , 136–158 View FIGURES 136–143 View FIGURES 144–150 View FIGURES 151–154 View FIGURES 155–158 )

Material examined. Holotype: female larva ready to molt to subimago, LAOS, river Mekong near lower end of island Don Det, 13°57'42"N, 105°54'55"E, 6–11.II.2025, coll. N. Kluge & L. Sheyko. GoogleMaps Paratype: the same locality, date and collectors: 1 female larva of penultimate instar GoogleMaps .

Etymology. The species name mekongiense refers to its inhabitance in river Mekong.

Larva. CUTICULAR COLORATION. Head mostly colorless, occipit with brownish maculae ( Fig. 138 View FIGURES 136–143 ). Pronotum and mesonotum with brown, ochre and colorless areas ( Fig. 137 View FIGURES 136–143 ). Metanotum and thoracic pleura with brown and colorless areas. Cuticle of legs mostly colorless. Abdominal terga with darker brown, lighter ochre and colorless areas; terga I, III, V–VI and IX darker than others ( Fig. 139 View FIGURES 136–143 ). Sterna colorless. Caudalii light ochre, with darker brownish margin of each 4th segment; swimming setae from ochre to colorless ( Fig. 139 View FIGURES 136–143 ).

HYPODERMAL COLORATION. Each abdominal tergum I–IX with unpaired longitudinal reddish stripe and pair of transverse reddish stripes near anterior margin; each tergum II and VIII with pair of reddish spots near lateral margins ( Fig. 140 View FIGURES 136–143 ).

SHAPE AND SETATION. Labrum widened distally, with distal margin sharply concave ( Fig. 144 View FIGURES 144–150 ). Mandibles with incisor and kinetodontium separated up to base ( Figs 145–146 View FIGURES 144–150 ). Maxilla modified as characteristic for Psammonella ( Fig. 150 View FIGURES 144–150 ). Maxillary palp with 3rd (terminal) segment shorter than 2nd segment ( Fig. 150 View FIGURES 144–150 ). Hypopharynx with 3 apices ( Fig. 149 View FIGURES 144–150 ). Glossae short and wide, with rounded margins, laterally longer than medially; paraglossae longer and narrower than glossae, arched, parallel-sided ( Figs 147–148 View FIGURES 144–150 ). 3rd (distal) segment of labial palp with inner angle stretched and distal margin concave ( Figs 147–148 View FIGURES 144–150 ).

Hind protoptera completely absent ( Fig. 139 View FIGURES 136–143 ).

Legs with thin, rather long, pointed, stout, two-channel setae located on inner sides of femur, tibia and tarsus; no stout setae on outer side of leg (as in Figs 131 View FIGURES 123–131 ). Claws long and slender, without denticles ( Figs 151–153 View FIGURES 151–154 ).

Abdominal segments II–VII with pair of posterolateral denticles; segments VII–IX with several denticles on lateral sides ( Fig. 155 View FIGURES 155–158 ). Posterior margin of abdominal tergum I without denticles; that of terga II–X with pointed denticles alternated with small denticles or blunt protuberances ( Fig. 155 View FIGURES 155–158 ). Posterior margins of abdominal sterna I–III without denticles; that of sterna IV–IX with pointed denticles shorter than denticles on terga ( Fig. 155 View FIGURES 155–158 ). Paraprocts with long, pointed denticles ( Fig. 155 View FIGURES 155–158 ). [Bifurcate setae on sterna not examined]

Tergalii ( Figs 39–45 View FIGURES 32–59 ) without dorsal lamella; tergalii I– V elongate; tergalius VI short and roundish; tergalius VII stretched posteriorly, of usual Procloeon - type ( Fig. 45 View FIGURES 32–59 ) .

In middle part of cerci and paracercus, denticles on posterior margin of each 4th segment nearly equally enlarged on dorsal and ventral sides ( Figs 157–158 View FIGURES 155–158 ). In distal part of cercus, greatly enlarged denticle on lateral side of each cercomere (peculiar for Procloeon ) widened at midlength and slightly longer than cercomere ( Fig. 156 View FIGURES 155–158 ).

Subimago (based on female subimago extracted from larva). CUTICULAR COLORATION. Cuticle very light or colorless; mesonotum colorless, only anterolateral scutal crest and prelateroscutum darkened with brownish ( Fig. 154 View FIGURES 151–154 ). Wing membrane entirely colorless, microtrichia ochre.

HYPODERMAL COLORATION. Wings crumpled under larval cuticle in proximal part dark gray, in distal part yellowish ( Fig. 154 View FIGURES 151–154 ). Legs of female with trochanter, femur, tibia and tarsus mostly light ochre, femur darkened with brown near base and near apex, tibia darkened with brown at outer side ( Figs 151–153 View FIGURES 151–154 ). Each abdominal tergum I–IX with unpaired longitudinal reddish stripe and pair of transverse reddish stripes near anterior margin; each tergum II and VIII with pair of reddish spots near lateral margins ( Figs 136, 140, 142–143 View FIGURES 136–143 ).

TEXTURE. In both sexes, on all leg pairs, all tarsomeres are covered with pointed microlepides (as in Figs 98–99 View FIGURES 98–102 ) (Kluge 2022).

Imago. Unknown.

Eggs. Unknown. Eggs extracted from mature female larva are undeveloped.

Comparison. Larva of the new species Procloeon ( Psammonella) mekongiense sp. nov. differs from Pr. ( Ps.) ceylonicum (Glazaczow in Jacob & Glazaczow 1987) by stretched inner angle of 3rd segment of labial palp. It differs from incompletely described Pr. ( Ps.) christinae ( Waltz & McCafferty 1989) at least by less shortened glossae, which have length exceeding width ( Figs 147–148 View FIGURES 144–150 ) (while glossae of P. christinae have length less than width— Waltz & McCafferty 1989: fig. 18).