Corresponding author: Thomas Kaltenbach (
Academic editor: K. Williams
Material collected in 1974 during the Austrian Hydrobiological Mission of F. Starmühlner to the Comoros and during recent years by one of the authors (NM) in the course of an ongoing freshwater monitoring program in Mayotte is the basis of this first larger study of the mayfly family
Kaltenbach T, Mary N, Gattolliat J-L (2021) The Baetidae (Ephemeroptera) of the Comoros and Mayotte. African Invertebrates 62(2): 427–463.
The family
The Comoros archipelago comprises four principal islands, from West to East: Grande Comore, Mohéli, Anjouan and Mayotte (Fig.
Maps:
The upstream part of the watercourses remains relatively well preserved from human activities, which allows the maintenance of a good water quality. On the other hand, a clear degradation is often observed downstream and at the mouths of streams. Several reasons have been identified to explain this degradation: urbanization: insufficient sewage systems and many houses without connection to a purification system; domestic and customary uses: traditionally, laundry is carried out directly in streams with products containing a high level of phosphates; washing cars in the rivers (hydrocarbons, used oil); this diffuse and chronic pollution leads to an increase in the pH of the water, eutrophication, and a reduction in biodiversity; industrial activities: pollution linked to limited or non-existent treatment of wastewater; agriculture: monocultures of bananas and cassava, slash-and-burn cultivation practices, or deforestation accelerate soil erosion, terrigenous transport in rivers and decrease in river flows; indirect uses: rivers collect unauthorized dumps like sachets of detergents, bottles of bleach, clothes, household waste, bulky items which all accumulate and cover the banks and beds of rivers, particularly in their downstream part. Each rainfall carries away significant amounts of waste into the waterways, and then to the sea.
The archipelago is subject to a humid tropical climate strongly influenced by the maritime environment and the direction of the winds. Two seasons are distinguished: a hot and rainy season from December to March with abundant and violent precipitation and a cooler dry season from June to September. Grande Comore, Anjouan and Mohéli are forming the Union of the Comoros, whereas Mayotte is an overseas department of France since March 2011.
In 1974, the Austrian Hydrobiological Mission collected aquatic animals in the Comoros, Mauritius, La Réunion and the Seychelles (
Here, we report eight species of
Mayotte is relatively well sampled due to the ongoing freshwater monitoring program, contrary to the Union of the Comoros, where collection activities remained geographically limited and without new sampling in the last 50 years. However, the mayfly fauna of the Comoros archipelago seems to be poorly diversified based on the results of the present study and previous ones.
Specimens were collected in 1974 during the Austrian Hydrobiological Mission of F. Starmühlner to the Comoros and during recent years by one of the authors (NM) in the course of an ongoing freshwater monitoring program in Mayotte. The nymphs were preserved in 70%-96% ethanol.
The dissection of nymphs was performed in Cellosolve (2-Ethoxyethanol) with subsequent mounting on slides with Euparal liquid, using an Olympus SZX7 stereomicroscope.
The DNA of part of the specimens was extracted using non-destructive methods allowing subsequent morphological analysis (see
Drawings were made using an Olympus BX43 microscope. To facilitate the determination of the new species and the comparison of important structures with other species, we partly used a combination of dorsal and ventral aspects in one drawing (see
Photographs of nymphs were taken using a Canon EOS 6D camera and processed with Adobe Photoshop Lightroom (
Approximate GPS coordinates to the older sample locations (1974) were attributed using Google Earth (
Coordinates of locations of examined specimens.
Species | Island | Location | Coordinates |
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Anjouan | Riv. Santsa |
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Mayotte | Riv. Bouyouni |
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Riv. Dembéni (middle course) |
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Riv. Djalimou |
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Riv. Koualé (trib. forest 3) |
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Riv. M’Tsangachéhi |
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Anjouan | Lac Sacré, Dzialandze |
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Grande Comore | Moroni (North of) |
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Mayotte | Riv. Bouyouni |
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Riv. Dapani |
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Riv. Dembéni (lower course) |
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Riv. Dembéni (middle course) |
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Riv. Djalimou |
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Riv. Haoutoungou |
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Riv. M’Tsangachéhi |
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Mayotte | Riv. Bouyouni |
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Riv. Coconi |
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Riv. Dembéni (lower course) |
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Riv. Dembéni (middle course) |
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Riv. Djalimou |
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Riv. Gouloué |
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Riv. Koualé (Loc. Légion) |
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Riv. Koualé (lower course) |
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Riv. Koualé (station 2) |
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Riv. Longoni |
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Riv. M’Tsangachéhi |
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Anjouan | Riv. Ouani |
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Riv. Tatinga (lower course) |
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Mayotte | Riv. Bouyouni |
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Riv. Chirini, Soulou |
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Riv. Coconi |
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Riv. Coconi, Barakani |
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Riv. Dembéni (lower course) |
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Riv. Gouloué |
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Riv. Koualé (Loc. Légion) |
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Riv. Koualé (lower course) |
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Riv. Longoni |
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Riv. M’Tsangachéhi |
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Riv. Ourovéni |
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Anjouan | Riv. Tatinga (lower course) |
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Anjouan | Riv. Tatinga (lower course) |
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Riv. Tatinga (upper course) |
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Anjouan | Riv. Santsa |
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Riv. Tatinga (upper course) |
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Anjouan | Riv. Foumbani |
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Riv. Santsa |
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Mayotte | Riv. Longoni |
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The terminology follows
1.
2.
3.
4.
5.
6.
7.
8.
Nymphs, habitus:
Both mandibles with lateral margins almost straight. Basal half with fine, simple setae scattered over dorsal surface.
(Fig.
Distribution of
In Mayotte, the specimens were collected at altitudes between sea level and 100 m, mostly together with one or several other species (
Comoros • 9 nymphs; Anjouan, Riv. Santsa, upper course, near Adda-Douéni; 750 m; 21.03.1974; leg. F. Starmühlner; 2 on slides; GBIFCH00592757, GBIFCH00592713; 7 in alcohol; GBIFCH00515654, GBIFCH00515708; MZL,
(Fig.
In the Comoros, the specimens were collected in a crater lake on the island of Anjouan at an altitude of 900 m and in a cistern with collected rainwater on Grande Comore (altitude 100 m). In Mayotte, the specimens were collected at altitudes from sea level to 100 m.
Comoros • 66 nymphs; Anjouan, Lac Sacré, crater lake, slope of N’Tingiu Mtns; 900 m; 12.03.1974; leg. F. Starmühlner; 2 on slides; GBIFCH00592748, GBIFCH00592749; 64 in alcohol; GBIFCH00515661, GBIFCH00515662, GBIFCH00515663; MZL,
Both mandibles with lateral margins almost straight. Basal half with fine, simple setae scattered over dorsal surface.
With reference to the island of Mayotte, where the type locality is.
(Fig.
Distribution of
The specimens were collected at altitudes between sea level and 110 m, mostly together with one or several other
(Fig.
Distribution of
In the Comoros, the specimens were collected at an altitude of approximately 200 m, together with
Comoros • 9 nymphs; Anjouan, Riv. Tatinga, lower course by the bridge; 210 m; 22.03.1974; leg. F. Starmühlner; 1 on slide; GBFCH00592742; 8 in alcohol; GBIFCH00515668, GBIFCH00515670; MZL,
The specimens were collected at an altitude of 210 m, together with
Comoros • 3 nymphs; Anjouan, Riv. Tatinga, lower course by the bridge; 210 m; 22.03.1974; leg. F. Starmühlner; 2 on slides; GBIFCH00592719, GBIFCH00592745; 1 in alcohol; GBIFCH00515665; MZL.
Nymphs, habitus:
Both mandibles with lateral margins almost straight. Basal half with fine, simple setae scattered over dorsal surface.
Dedicated to the late entomologist Barton A. Richard (formerly Florida A&M University, Tallahassee), who participated in an early phase of this project (2004–2007).
(Fig.
Distribution of
The specimens were collected at altitudes of 210 m and 600 m, together with
The specimens were collected at altitudes of 600 m and 750 m, together with
Comoros • 5 nymphs; Anjouan, Riv. Tatinga, upper course, near Dindri; 600 m; 11.03.1974; leg. F. Starmühlner; 4 on slides; GBIFCH00592753, GBIFCH00515707, GBIFCH00592725, GBIFCH00592709, GBIFCH00592712, GBIFCH00592710; 1 in alcohol; GBIFCH00515659; MZL,
In the Comoros, the specimens were collected at altitudes of 150 m and 750 m, partly together with
Comoros • 2 nymphs; Anjouan, Riv. Foumbani, Foumbani, near Sima; 150 m; 26.03.1974; leg. F. Starmühlner; 1 on slide; GBFCH00592756; 1 in alcohol; GBIFCH00515657; MZL • 2 nymphs; Anjouan, Riv. Santsa, upper course, near Adda-Douéni; 750 m; 21.03.1974; leg. F. Starmühlner; 1 on slide; GBIFCH00592755; 1 in alcohol; GBIFCH00515658;
1 | Legs stocky with tibiae and tarsi almost fused, claws short and without denticles |
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– | Legs elongated with free tibiae and tarsi, claws with denticles |
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2 | Claws elongated, with numerous denticles; at least part of the gills formed by two lamellae; abdominal segments VI–IX laterally with strong, apically pointed spines |
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– | Claws not elongated, with less than 15 denticles; all gills formed by a single lamella; abdominal segments VI–IX laterally without spines |
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3 | Upper lamella of gills rounded, almost as developed as lower one |
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– | Upper lamella of gills elongated, sometimes as long as lower one, but much narrower |
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4 | Antennae close to each other with small carina in between; posterior margin of tergite IV with discontinuous row of few reduced, triangular spines (Fig. |
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– | Antennae without carina in between; posterior margin of tergite IV with continuous row of triangular spines |
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5 | Labial palp segment II with large distomedial protuberance; maxillary palp segment II with distolateral excavation; mandibles without setae between prostheca and mola; fore tibia with patellotibial suture ( |
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– | Labial palp segment II without distomedial protuberance; maxillary palp segment II without excavation; at least right mandible with setae between prostheca and mola; fore tibia without patellotibial suture (Protopatellata) |
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6 | Seven pairs of gills; hind protoptera well developed |
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– | Six pairs of gills; hind protoptera absent or vestigial |
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7 | Incisor of both mandibles blade-like, kinetodontium with denticles (Fig. |
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– | Incisor and kinetodontium of both mandibles with denticles (Fig. |
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The nymph described in this study (Figs
The Comoros are poorly diversified and no other
The genus
However, for both
The Panafrotropical species
Remarkably, the Malgasy
A thorough comparison of the specimens from Comoros with the type series from Madagascar did not reveal any morphological differences. Nevertheless, we recommend comparing the genetics (
In the original description of
The Comoros archipelago expands nearly half way between the African continent and the island of Madagascar and thus could have served as stepping stones for a faunal exchange between Africa and Madagascar in both directions. The distribution and morphological affinities of the
Based on this study and other studies in the past, the mayfly fauna of the Comoros archipelago seems to be poor. Mayotte is well sampled due to the long-term and still ongoing freshwater monitoring program, contrary to the Comoros, where collection activities remained very limited in the past. Mohéli was not sampled for more than a century, the fauna of this island remains virtually unknown apart from the original report of
We extend our deepest thanks to the Austrian Hydrobiological Mission of 1974 to the Seychelles-, Comoros- and Mascarene Archipelagos and to the late Ferdinand Starmühlner (formerly University of Vienna) for the collection of precious material and to make it available to the Florida A&M University (