Cheleocloeon Wuillot & Gillies 1993

Kluge, Nikita J., 2025, Two new species of the genus Cheleocloeon Wuillot & Gillies 1993 (Ephemeroptera: Baetidae) from Tanzania and corrections to the generic diagnosis, Zootaxa 5660 (3), pp. 330-350 : 331

Genus Cheleocloeon Wuillot & Gillies 1993

( Figs 1–82 )

Type species: Cheleocloeon yolandae Wuillot (in Wuillot & Gillies) 1993.

Diagnosis of Cheleocloeon was given in the previous paper ( Kluge 2016). Characters of the new species Ch. psammonella sp. nov., partly disagree with this diagnosis, so the generic diagnosis should be modified as following.

Point (3): Labrum. Distal margin of labrum varies from usual for most Baetidae ( Fig. 8 ) to concave ( Fig. 56 ).

Point (5): Maxillae. Maxillary canines vary from long and slender ( Fig. 11 ) to fused forming short, flat, wide and blunt plate ( Figs 62–63 ).

Point (7): Labium. Glossae and paraglossae vary from pointed, both with a regular dorso-lateral row of long setae ( Figs 12–13 ) to blunt, with numerous irregularly situated long setae on apex of paraglossa ( Fig. 64 ).

Points (1)–(2), (4), (6), (8)–(24) of the diagnosis are unchanged.

Figures

FIGURES 1–7. Cheleocloeon acutipalpum sp. nov.: larvalexuviae. 1–4, abdomen,head, pronotumwith mesonotum, metanotum of male specimen from Matema; 5, thoracic pleura with legs and half of metanotum of female specimen from Matema; 6–7, pronotum with mesonotum and abdomen of male specimen from Amani (holotype).

FIGURES 8–14. Cheleocloeon acutipalpum sp. nov.: larval exuviae. 8, labrum; 9–10, left and right mandibles; 11, maxilla; 12–13, labium with focus on dorsal and ventral sides; 14, enlarged fragment of labial palp.

FIGURES 15–17. Cheleocloeon acutipalpum sp. nov.: larval exuviae of legs. 15, fore leg; 16, middle leg; 17, hind leg.

FIGURES 18–22. Cheleocloeon acutipalpum sp. nov.: larval exuviae. 18, claw; 19, fragment of fore femur; 20, abdominal sternum IX and paraprocts of male; 21, abdominal tergum III; 22, fragment of caudalii (18, 21, holotype).

FIGURES 23–30. Cheleocloeon acutipalpum sp. nov. 23, last instar female larva just after molt, with colorless cuticle, to show hypodermal coloration; 24–30, tergalii of I–VII pairs.

FIGURES 31–37. Cheleocloeon acutipalpum sp. nov.: male imagines. 31, dorsal view; 32, abdominal terga and sterna; 33–34, lateral view; 35, hind wing; 36–37, fore and hind legs (34–37, holotype).

FIGURES 38–43. Cheleocloeon acutipalpum sp. nov. 38–40, 42, male imaginal genitalia, ventral view; 41, the same, with focus on gonovectes; 43, exuviae of subimaginal gonostyli (38–39, holotype).

FIGURES 44–49. Cheleocloeon acutipalpum sp. nov. 44, female imago; 45–47, subimaginal exuviae (45, mesopleuron; 46, half of mesonotum; 47, abdomen); 48–49, eggs (46, holotype).

FIGURES 50–55. Cheleocloeon psammonella sp. nov. (holotype). 50–54, parts of larval exuviae at the same magnification (50, abdomen, 51, half of pronotum and mesonotum, 51, head, 53, fore leg, 54, half of metanotum and hind leg); 55, exuviae of fore leg.

FIGURES 56–60. Cheleocloeon psammonella sp. nov., larval exuviae (holotype). 56, labrum; 57–58, left and right mandibles; 59, maxilla (see Figs 61–63); 60, labium (see Figs 64–66).

FIGURES 61–63. Cheleocloeon psammonella sp. nov., maxillae (holotype). 61, with focus on dorsal side; 62–63, with focus on ventral side. Abbreviations: can, fused and flattened maxillary canines forming apical plate; ds1, ds2, ds3, dentisetae; m-v, setae of medio-ventral row.

FIGURES 64–66. Cheleocloeon psammonella sp. nov., labium (holotype). 64, dorsal view (most setae not shown); 65–66, ventral view.

FIGURES 67–72. Cheleocloeon psammonella sp. nov., larval exuviae (holotype). 67, abdominal sternum and tergum IX; 68, tergum X; 69, paraproct; 70, part of tergum VI; 71, distal part of cercus; 72, middle part of cerci and paracercus.

FIGURES 73–78. Cheleocloeon psammonella sp. nov. (holotype). 73–76, tergalii I–IV; 77–78, tergalii VI–VII.

FIGURES 79–82. Cheleocloeon psammonella sp. nov., (holotype). 79, genitalia of male subimago with gonostyli non-spread and retaining folded condition as if being under larval cuticle; 80, right gonovectis and its muscle; 81, head and thorax of male subimago; 82, subimaginal exuviae of right half of mesonotum.