Leptohyphes alleni Brusca, 1971

Baumgardner, D. E. & Mccafferty, W. P., 2010, Revision of the genus Leptohyphes Eaton (Ephemeroptera: Leptohyphidae) in North and Central America, Zootaxa 2360 (1), pp. 1-33 : 4-8

Leptohyphes alleni Brusca

Leptohyphes alleni Brusca, 1971:146 ; Allen, 1978:543.

Diagnosis: Based upon the original description, larvae of L. alleni are distinguished from other known Leptohyphes larvae by the presence of numerous small, pale spots (see “Discussion” below for comments concerning this character) on the head, body, and appendages, which are absent in all other species, except L. murdochi , which also possesses pale spots on the body. Leptohyphes murdochi larvae can be distinguished from L. alleni larvae due to the presence of a distinct apical concavity on the middle and hind femora, which are absent on L. alleni larvae.

Description: Male Adult: Unknown. Larva: Length. Body, 4.5–5.5 mm; caudal filaments, 4.0–5.0 mm. General coloration very pale yellowish-brown. Head: pale yellowish; antennae pale. Thorax: pale yellowishbrown; without anterolateral projections and median tubercle. Legs. Proleg (Fig. 18): femur with transverse row of robust setae and numerous, small, shallow circular pits on dorsal surface; anterior and posterior margins with few, scattered filiform setae; tibia with evenly spaced row of filiform setae along anterior margin, and single row of elongate setae along anterolateral margin; posterior margin with few, scattered filiform setae; tarsus with evenly spaced filiform setae along inner margin; posterior margin with a few, scattered filiform setae along outer margin. Meso- and metalegs ( Fig. 22F ): femora densely covered with numerous, small, shallow circular pits on dorsal surface; setae absent from dorsal surface; anterior margin with few, scattered stout setae; basal half of posterior margin with scattered filiform, and elongate setae along most of distal margin; tibiae with elongate setae present along most of anterior and posterior margins; tarsus with setae absent from anterior margin, and single row of filiform setae along posterior margin. Claws of all legs with three to four marginal denticles ( Fig. 23D ); submarginal denticle absent. Abdomen: terga pale yellowish-brown; sublateral margins of tergites seven and eight without setae ( Fig. 25D ); operculate pale; gill formula 2/5/5/5/2.

Distribution: Known only from the type locality in Oaxaca, Mexico.

Discussion: Leptohyphes alleni was described by Brusca (1973) on the basis of four larvae from a single location in Oaxaca, Mexico. No additional collection records of it have been reported in the literature since its original description. The holotype (a mature female larva) and paratypes of L. alleni are badly faded and show no “pale spots”, as described in the literature. What appear as pale spots on the abdominal tergites of the holotype female larva are the underlying eggs. The dorsal surface of all legs are densely covered with small, shallow pits which are paler than the surrounding coloration of the leg. These may have been the “pale spots” to which Allen was referring. However, no similar structures could be found on the head or body. These pale spots do not appear to be simply changes in coloration, but possibly some type of shallow pits perhaps used for chemical reception. There exact function of these pits is unclear.

FIGURES 18–20. Leptohyphes alleni , larva. 18, foreleg (dorsal) [C]. 19, hindleg (dorsal) [C]. 20, hindclaw (ventrallateral) [F]. Scale bars (mm): A, E = 0.5; B = 0.2; C, F = 0.1; D = 1.0. bs = basal spines; lr = longitudinal ridge; mel = median elevated ridge; plp = posterior lateral projections.

The type specimens are all badly faded and do not show any of the darker reddish-brown coloration as described in the original description ( Brusca, 1971), or by Allen (1978). In addition, none of the black markings are present as originally described, such as the black band between the compound eyes, or black markings on the thorax, abdomen, or operculate gills. Coloration in the above description is based upon the current coloration of the larvae.

All legs have been removed from the holotype, and possibly mounted on slides associated with the type series; however, it is unclear which slides are associated with the holotype, and which with the paratypes. Tarsal claw denticulation and shape of the profemur do agree with the original description.

Type material examined: Leptohyphes alleni HOLOTYPE (larva): MEXICO, Oaxaca, stream 10 miles N. Huajuapan de Leon (elev. 5,400 ft), 07.xi.1968, RKA [ CAS #13600 ] . PARATYPES: same data as holotype, 3L, 5 slides (unknown which slides belong with holotype and which belong with paratypes) [ CAS] . Other material examined: None.

Figures

FIGURES 21–25. Leptohyphes apache, larval structures. 21, head and prothorax, [scale bar B]. 22, foreleg [D]. 23, hindleg [E]. 24, hind claw (ventro-lateral) [C]. 25, abdominal tergites 7-10 [A]. Scale bars (mm): A, B = 0.05; C = 0.1; D = 0.5; E = 0.4.