Complementary description of the genus Manohyphella Allen, 1973 (Insecta: Ephemeroptera: Teloganodidae), with some comments on its ecology in the Andasibe area (East Coast, Madagascar)

Based on a large collection of material from the East Coast of Madagascar, we redescribe the endemic genus and species Manohyphella keiseri Allen, 1973. The male imago is described for the first time and details on the nymphal stage is provided, especially on the gill formula. The species M. animosa McCafferty & Benstead, 2002 and M. sphyxia McCafferty & Benstead, 2002 are considered as subjective junior synonyms of M. keiseri Allen, 1973. Notes on the life cycle of the species in the Andasibe area is presented, as well as data about the density of the populations. M. keiseri is an inhabitant of pristine running waters in rainforests and is therefore a good indicator for habitat quality.


Introduction
The genus Manohyphella (type species Manohyphella keiseri Allen, 1973) was first proposed for some female imagos captured on the East Coast of Madagascar. They were characterized by the peculiar shape of the hind wing, with a pointed costal process located in the posterior half of the wing (Allen 1973). At the time, the genus was placed in the subfamily Teloganodinae within the family Ephemerellidae. Teloganodinae was later raised to the family level (McCafferty and Wang 1997), and its composition circumscribed in a subsequent paper (McCafferty and Wang 2000).
The female of Manohyphella was the only stage known until McCafferty and Benstead (2002) which described the nymph and proposed two new species, M. animosa and M. sphyxia, mentioning that one of them could in fact be the true nymph of M. keiseri.
During research lead by the LRSAE in Madagascar from 1991 to 1999 (see Elouard and Gibon 2001 for a review of the programme), numerous Manohyphella nymphs were collected, and one was successfully reared to the male imaginal stage. This gives us the opportunity to describe the male imago, and to bring complementary information on the nymphal stage, especially the gills. Due to the broad range of our Manohyphella collection, intraspecific variation is considered and some taxonomic changes proposed.
More recently, field work was conducted for one year in the area of Andasibe (East Coast) by Ranalison Oliarinony, where populations of Manohyphella, among other macroinvertebrates, were sampled each month. We present some ecological data concerning the genus, especially its life cycle.

Material examined (all from Madagascar)
The examined material is deposited in the collections of the Musée cantonal de Zoologie, Lausanne (MZL) and in the collections of the Florida A & M University, Tallahassee (FAMU).

Ecology and life cycle
Six streams belonging to the Rianila watershed (7820 km 2 ) were studied. They are all located in the Eastern Domain, once entirely covered with rainforest, and now heavily altered by human activities. Three sites (Belakato BT, Madiofasina MA, Rianasoa RA) are located in the Mantadia National Park, in primary forests, whereas three others (Antanambotsira AA, Sandrasoa SA, Sahaparasy SY) are located in degraded, open canopy areas composed of Tavy (traditional form of slash-and-burn agriculture, mainly for rice culture) and Savoka (fallow fields). All localities belong to second or third order streams. Characteristics of the localities are given in Table 1.
Monthly samplings were performed in each locality from June 2001 until June 2002, with the exception of November 2001 (bimonthly samplings) and March 2002 (no samplings due to heavy rains at the end of the wet season). A Surber net of 0.1 m 2 , mesh size of 250 µm was used with three replicates at each site. Material was then fixed in ethanol for further studies. Head width (HW) of all specimens was measured to the nearest 0.1 mm using a stereomicroscope and an eyepiece micrometer. Mature larvae (recognizable by their black wing pads) were sexed and measurements used to investigate sizes at emergence. Density is expressed as mean number of individuals m -2 , and biomass was derived from mean density and length-mass relationships as proposed by Benke et al. (1999) for the genus Serratella (DW = ln(0.7255) + 3.325*lnHW). Results are expressed in mg dry weight (DW) m -2 .
Meso-metathorax: medium brown, washed with grey; coxa and trochanter washed with black, femur medium brown with two longitudinal blackish stripes, femoro-tibial articulation blackish, tibia and tarsus light brown; tarsal claw dissimilar. Forewing ( Fig. 1) translucent with base tinted with dark brown; longitudinal veins medium to light brown, crossveins translucent; a single intercalary between IMP and MP2, one between MP2 and CuA, and three between CuA and CuP; hindwing (Fig. 2) entirely dark brown, costal process pointed and located ca ⅓ along the tip of the wing; mesoscutellum with well-developed posterior processes.      Allen, 1973 adult (5) and larva (6-10). 5 male genitalia in ventral view 6 gill I 7 gill II 8 gill III 9 gill IV 10 gill V. Scale bar: 0.2 mm (6-10). Abbreviations: dl dorsal lamella vl ventral lobes.
Abdomen: tergites greyish brown, colour intensity increasing toward the tip; presence of two rounded and whitish spots in postero-lateral position of each segment, especially well marked on segments VI-IX; abdominal sternites light grey. Genitalia (Fig. 5): styliger plate light brown, with a rounded process in the middle of the posterior margin; gonopods light brown, three-segmented, the first one stout, just over half the length of segment II; segment III ovoid and short; inner margin of gonopods bearing stout and short scale-like setae; penes lobes medium brown stout and almost completely fused except at the tip, shorter than the gonopods; no spines or ornamentation present. Cerci broken.
Similar to the male, except as follows: legs uniformly light brown; forewing ( Fig. 3) with subcostal field entirely brownish, hind wing (Fig. 4) light brown, with costal process located ca ⅕ of the tip of the wing; abdominal patterns visible but less contrasted, sternites greyish brown; subanal plate slightly incised in the middle; cerci entirely whitish.
Female subimago. Similar to the adult female, except general coloration reddish brown, wings entirely medium brown, subanal plate regularly rounded. Nymph (Fig. 11). The species has been described by McCafferty and Benstead (2002), with the following important complements: Patch of setae on the outer margin of the mandibles variable in number and often broken, their insertion only visible at high magnification. Maxilla with a spoon-like tooth, and with two stout and curved dentisetae; patch of setae at the base of the galea composed of 2-5 long, thin setae. Labium with submentum well developed, anterolateral corners more or less rounded; base of the 3 rd segment of the labial palp as wide as the articulation with the 2 nd segment.
Gills (Figs 6-10) present on segments I-V. Gill I (Fig. 6) small, finger-like and one segmented, covered with long and thin setae. Gill II (Fig. 7) with a plate like dorsal lobe, and a ventral lobe constituted of costal and anal branches, dorsal gill more or less quadratic, with a distinct longitudinal ridge. In the distal ¼ of the dorsal lobe, a weak line well visible and almost reaching the middle of the plate, probably allowing the larva to lift the distal part of the gill. Dorsal plate of gill III (Fig. 8) quadratic, outer margin concave and with long, thin setae. Dorsal plate of gill IV (Fig. 9) transverse, with long, thin setae on the margin. Gill V (Fig. 10) identical to the previous one, smaller and without ventral lobe. Single postero-median tubercles on tergites variable in size and orientation depending on the developmental stage of the larva. Cerci and terminal filament with rows of stout, long setae.
Ecology. Manohyphella keiseri larvae were almost exclusively found in the three forested localities (BT, MA, RA) and were virtually absent from the Savoka open canopy localities (4 specimens captured in the three localities in one year), confirming that the species is strictly bound to the forest cover. Populations in BT were not dense enough to proceed to life cycle analyses. Mean densities in MA and RA over the investigated period were 12.50 ± 17.93 and 10.56 ± 11.18 ind. m -2 respectively. Mean biomass was 8.17 and 7.07 mg DW m -2 respectively. The life cycle exhibits a seasonal pattern which is not characteristic of tropical species (Fig. 12). Mature nymphs were found between September and November, at the end of the dry season.

Morphological description
Relationships of Manohyphella with other Teloganodidae have been already discussed by McCafferty and Benstead (2002) as well as by Sartori et al. (2008) who included what they called M. animosa in their phylogenetic reconstruction of the Oriental lineage. Manohyphella is clearly more closely related to the Afrotropical lineage than to the Oriental one: presence of a well developed terminal filament, patch of setae on the outer margin of the mandibles, are two important characters shared between all Afrotropical genera (Ephemerellina Lestage, 1924, Lestagella Demoulin, 1970, Lithogloea Barnard, 1932, Nadinetella McCafferty & Wang, 1998, including Manohyphella. Very recently, two new teloganodid genera have been described from India (Selvakumar et al. 2014), which also possess a well developed terminal filament. One of them (Janohyphella Selvakumar, Sivaramakrishnan & Jacobus, 2014) does not belong to Teloganodidae (Kluge et al. 2015); the other one, Indoganodes Selvakumar, Sivaramakrishnan & Jacobus, 2014, does not bear patches of setae on the outer margin of the mandibles, abdominal tergites bear poorly developed median tubercles, incisors of the mandibles are not spoon-shaped, and the shape of the legs is much more slender compared to Manohyphella.
Here we describe for the first time the gills composition and it appears that Manohyphella possesses a unique combination of characters among Teloganodidae (Kluge 2004, table 8, page 297). Manohyphella bears gills on segments I-V, the first one finger-like, gills II-IV with an entire dorsal lobe and a ventral lobe and a gill V with only an entire dorsal lobe. The closest relative is Nadinetella crassi (Allen & Edmunds, 1963) from the Cape Province in South Africa which possesses almost the same formula except that gill V bears a ventral lobe.
As mentioned by Allen (1973), the forewing venation in the median and cubital fields seems constant among the material examined and differs from all other Teloganodidae. The male genitalia are also different from the other Afrotropical ones, being less stocky compared to Lithogloea harrisoni Barnard, 1932, without divergent apical lobes, as in Nadinetella crassi and more stout at base compared to those of Ephemerellina barnardi Lestage, 1924or Lestagella penicillata (Barnard, 1940) (Pereira-da-Conceicoa and Barber-James 2013).
The wide geographical range where Manohyphella has been found allows us to consider the morphological variation encountered in the nymphs. McCafferty and Benstead (2002) separated M. animosa from M. sphyxia mainly by the shape of the postero-lateral corners of the submentum, as well as by the shape of the tubercles on the tergites. We have been through all material available and found both characters subject to variations; the tubercles vary in structure depending on the developmental stage, whereas the submentum presents different development of the postero-lateral corners, from clearly rounded to more acute; moreover this structure is delicate and subject to being distorted during slide mounting, hence changing its normal shape. Comparison of morphological characters of other mouthparts, and legs showed no clear-cut separation allowing attribution of some populations to different species.
It is moreover amazing to see that the three nominal species have been described from the same area (Ranomafana National Park and surroundings), one of them, M. sphyxia based only on a single female nymph. Our winged material from Manampatrana perfectly fits the generic and specific diagnosis proposed by Allen (1973), and is similar to the type material (deposited in the Naturhistorisches Museum, Basel, Switzerland) of M. keiseri. Therefore, we conclude that a single species is present in the available material and consequently, M. animosa Benstead, 2002 andM. sphyxia McCafferty &Benstead, 2002 are considered as subjective junior synonyms of M. keiseri Allen, 1973. To date, Manohyphella is therefore a monospecific endemic genus of Madagascar.

Ecology and life cycle
Our results concerning habitat preferences are in accordance with those obtained by Benstead et al. (2003) in Ranomafana area. M. keiseri is an inhabitant of pristine tropi-cal forested streams obviously very sensitive to habitat degradation. This characteristic is probably found in other teloganodid species, as demonstrated by Mantel et al. (2010) who show that South African Teloganodidae in general were among the most sensitive taxa to the impact of dams. Densities in our study sites are higher than in Benstead et al. (2003) study (5.3 ± 4.3 ind. m -2 ). M. keiseri biomass is lower than those of other mayflies studied (Oliarinony unpubl. results), especially Baetidae which can be two to four times higher. As these are the first quantitative results for the family Teloganodidae, no comparison can be made with other species in South Africa or in Asia.
It is difficult to interpret the cycle in detail because the number of specimens is not high enough. Our graph ( Figure 12) suggests a seasonal life cycle with adults emerging at the end of the dry season. Aseasonality in the tropics is well documented and common in aquatic life histories (Yule and Pearson 1996;Salas and Dudgeon 2003). The presence of young larvae in September, together with mature ones, could indicate either recruitment from a previous generation (i.e. at least a bivoltine cycle) or a de- Figure 13. Map of known specimens of M. keiseri, with detailed map of the Andasibe area. Yellow pins: new localities; red pin: type locality (Ranomafana); green pins: localities in Andasibe area. Code of the localities according to Table 1. layed hatching of the last generation of the year before. Thus, we cannot exclude that M. keiseri is univoltine in the study area.
Easy to identify at the nymphal stage and with a distribution restricted to pristine environments, M. keiseri is therefore a good bioindicator for environmental assessments.