Cloe tristis Hagen, 1858

Sartori, Michel, Peters, Janice G. & Hubbard, Michael D., 2008, A revision of Oriental Teloganodidae (Insecta, Ephemeroptera, Ephemerelloidea), Zootaxa 1957 (1), pp. 1-51 : 3-4

Redescription of Cloe tristis Hagen, 1858

The type series # 33520 contains 4 pinned specimens that are syntypes of Cloe tristis . One specimen is a female imago and the last three are female subimagos. The imago and two subimagos are in poor condition with wings, head or abdomen missing. The last female subimago is in good condition and has been designated as lectotypus. It bears the following labels:

i) MCZ Type 33520 3 [red label]

ii) Hagen. [white label typewritten]

iii) 21. [green label typewritten]

iv) Ceylon Nietner [white label handwritten]

This specimen has been treated with trisodic phosphate 0.35% for 24 hours and then removed from the pin and stored in 75% ethanol ( Van Cleave & Ross 1947). Original labels are kept dried with the naked pin, whereas the lectotypus bears a copy of the information.

Condition. Left hindleg, right fore- and hindlegs missing.

Size. Body length: 6.5 mm; forewing length: 10.2 mm; hindwing length: 1.5 mm.

Description. General colouration medium brown; thorax dark brown; mesoscutellum without posterior processes. Legs yellowish-brown, claws dissimilar, one obtuse, the other hooked; tarsi without distal hump; tibiae and tarsi covered with setae. Wings uniformly light brown, without any markings. Forewing almost acute at the apex, pterostigmatic area with 4–6 crossveins; numerous crossveins in the radial field; MP 2 well developed but not connected to MP 1; 4 intercalary veins between CuA and CuP ( Fig. 1 ). Hind wing broad: ratio length/width (measured according to Hubbard 1995), ca. 1.5. Three longitudinal veins visible, the middle forked before the costal process. Two cross veins visible just under the costal process that is asymmetrically rounded ( Fig. 3 ).

Abdominal terga dark brown, tinted with black markings laterally; posterolateral spines visible on segments VII–IX. Gill sockets visible on segments II–VI; subanal plate slightly pointed.

Cerci whitish, with dark rings at each segment; median filament absent.

Eggs pear-shaped; chorionic surface covered by a polygonal mesh; one polar cap, well developed and attached to egg by sharp triangular structures ( Fig. 102 ); opposite pole without accessory structures.

Discussion. The specimen examined here fits the description and illustration given by Eaton (1884, plate XV, fig. 24bis), especially in the shape and venation of the wings; however, the most striking character concerns the abdomen and the gill socket vestiges. It is known, especially in ephemerelloid mayflies, that the subimaginal skin retains traces of the gill insertions present in the nymph. Knowing that position of the nymphal gills is critical in the taxonomy of Ephemerelloidea, [“the characteristic of gill socket vestiges on the adult abdomen is obvious and simple to use” ( McCafferty & Wang 2000, p. 42)], and allows, at least at the generic level, the association of nymphal and adult stages.

The current concept of Teloganodes , especially T. tristis , is derived from Ulmer’s work (1939). In his description, the author mentioned gills present on segments II–V (p. 630). This character was confirmed later by McCafferty & Wang (1997) and Tong & Dudgeon (2000). As the female subimago lectotypus of T. tristis bears gill socket vestiges on segments II–VI, we can conclude that the nymph must have gills on segments II– VI. Consequently, the concept of T. tristis sensu Ulmer (1939) and subsequent authors is obviously not the same as Hagen’s concept. The nymph described by Ulmer cannot belong to T. tristis , nor can the adult stages described by him and others (e.g. Ulmer 1924 and subsequent authors).

The genus Macafertiella Wang is known only at the nymphal stage and is easily told from Teloganodes sensu Ulmer by the presence of gills on segments II–VI ( Wang & McCafferty 1996). These authors predicted that, although unknown, the adults of Macafertiella will have “gill socket vestiges on abdominal segment [sic] 2–6” ( McCafferty & Wang 1997, p. 406). It becomes then extremely credible that Macafertiella represents the immature stage of Teloganodes Eaton. Accordingly , the genus Teloganodes must be redefined and “ T. tristis” sensu Ulmer, 1939 must represent another taxon.

Figures

FIGURES 1–6. Teloganodes spp. Fig. 1: Forewing of the female subimago lectotype of Teloganodes tristis (Hagen) [MCZ]; Fig. 2: Forewing of a male subimago syntype of Teloganodes major Eaton [MCZ]. Fig. 3: Hindwing of the female lectotype of Teloganodes tristis (Hagen) [MCZ]; Fig. 4: Hindwing of the male holotype of Teloganodes dentatus Navás [MNHN]; Fig. 5: Genitalia of a male subimago syntype of Teloganodes major Eaton [MCZ]; Fig. 6: Genitalia in ventral view of the male holotype of T. dentatus Navás [MNHN].

FIGURES 98–102. Egg structure of Teloganodes hubbardi (98–101, SEM pictures) and T. tristis (102, light microscope). Fig. 98: Shape of the egg; Fig. 99: Detail of the polar cap; Fig. 100: Micropyle area and crown of sets; Fig. 101: Detail of the uncoiled tread of the epithema; Fig. 102: Partial view of polar caps where crown and uncoiled threads are visible.