Research Article |
Corresponding author: Thomas Kaltenbach ( thomas.kaltenbach@bluewin.ch ) Academic editor: Lyndall Pereira-da-Conceicoa
© 2022 Thomas Kaltenbach, Laurent Vuataz, Boudjéma Samraoui, Sara El Yaagoubi, Majida El Alami, Jean-Luc Gattolliat.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kaltenbach T, Vuataz L, Samraoui B, El Yaagoubi S, El Alami M, Gattolliat J-L (2022) Two new species of Centroptilum Eaton, 1869 from North Africa (Ephemeroptera, Baetidae). ZooKeys 1131: 71-97. https://doi.org/10.3897/zookeys.1131.91017
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Based on recently collected larvae from Algeria and Morocco, the species delimitation within the genus Centroptilum Eaton, 1869 in that region is validated. Two new species are described and illustrated, one from north-eastern Algeria, and one from North Morocco, using an integrated approach with morphological and molecular evidence. A table summarising the morphological differences between the new species and Centroptilum luteolum (Müller, 1776) from Central Europe is provided. Further, molecular evidence for additional undescribed species of Centroptilum in other regions of the West Palearctic is provided and discussed.
Algeria, biogeography, COI, mayflies, Morocco, Palearctic, taxonomy
The genus Centroptilum Eaton, 1869 originally encompassed only the two species distributed in Europe and North America. It was, at that time, mainly defined by imaginal characters, adults being mostly similar to Cloeon Leach, 1815, but different by the presence of narrow hindwings with a long costal process. The generic concept was rapidly broadened to encompass all Baetidae with single intercalary veins and presence of hindwings. Species from all biogeographical regions, including Australasia, were assigned to this genus with the highest diversity in the Afrotropical and Nearctic regions. The generic concept was step by step circumscribed mainly by excluding the Afrotropical species and creating new genera to accommodate them (
The genus Centroptilum was reported from the whole Maghreb. In Tunisia, the genus seems to be extremely rare as
The specimens from Algeria were collected between 2018 and 2020 by BS, and the specimens from Morocco in 2014 and 2021 by MEA and collaborators. Comparative material from Switzerland was collected by André Wagner (MZL). The larvae were preserved in 70%–96% ethanol.
The dissection of larvae was done in Cellosolve (2-Ethoxyethanol) with subsequent mounting on slides with Euparal liquid, using an Olympus SZX7 stereomicroscope.
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 the same drawing (see
Centroptilum samraouii sp. nov., larva morphology a labrum (left: ventral view; right: dorsal view) b right mandible c right prostheca d left mandible e left prostheca f hypopharynx and superlinguae g maxilla h seta, ventrolateral i glossa and paraglossa (left: ventral view; right: dorsal view) j labial palp (left: ventral view; right: dorsal view).
Photographs of larvae were taken using a Canon EOS 6D camera and processed with Adobe Photoshop Lightroom (http://www.adobe.com) and Helicon Focus v. 5.3 (http://www.heliconsoft.com). Photographs of body parts of the larvae were taken with an Olympus BX51 microscope equipped with an Olympus SC50 camera and processed with Olympus (recently Evident) software Stream Basic v. 1.3. All pictures were subsequently enhanced with Adobe Photoshop Elements 13.
Distribution maps were generated with SimpleMappr (https://simplemappr.net,
Species | Country | Location | Coordinates | Specimen catalogue # | GenBank #(CO1) | GenSeq Nomenclature |
---|---|---|---|---|---|---|
Centroptilum samraouii sp. nov. | Algeria | Louar inf. | 36°37'03"N, 08°22'49"E | GBIFCH00763735 | OP113123 | genseq-2 COI |
Guitna sup. | 36°36'42"N, 08°21'19"E | GBIFCH00895417 | OP113124 | genseq-2 COI | ||
GBIFCH00895418 | OP113125 | genseq-2 COI | ||||
GBIFCH00654969 | OP113126 | genseq-2 COI | ||||
Guitna inf. | 36°37'05"N, 08°20'47"E | GBIFCH00975621 | n/a | n/a | ||
Centroptilum alamiae sp. nov. | Morocco | Oued Kelâa | 35°14'32"N, 05°10'10"W | GBIFCH00980875 | OP113127 | genseq-2 COI |
GBIFCH00980876 | OP113128 | genseq-2 COI | ||||
Oued Jnane Niche | 35°15'29"N, 04°52'42"W | GBIFCH00975647 | n/a | n/a | ||
Centroptilum sp. | Iran | Javarem | 36°13'43"N, 52°54'32"E | GBIFCH00763741 | OP113129 | genseq-4 COI |
For the molecular part of the study, we first downloaded all Centroptilum cytochrome oxidase subunit 1 (COI) sequences available on GenBank as on 13.04.2022 using a custom script, resulting in 99 records. We then manually removed all sequences from specimens collected outside the Western Palearctic, resulting in 34 European sequences for further analyses. We also examined the sequences available on the BOLDSYSTEMS data portal as on 13.04.2022, but excluded all sequences shared with GenBank, those from specimens collected outside the Western Palearctic, and one sequence that did not blast with Centroptilum (i.e., most probably resulting from a misidentification or a contamination). As a result, no additional sequence could be obtained. We also included three sequences from the European mayfly FREDIE project (unpublished; https://wp.fredie.eu/). Finally, seven specimens were newly sequenced for this study (Table
To explore COI evolutionary divergence and compare it to our morphological identifications, we applied three single-locus species delimitation methods to our CO1 data set: the distance-based ASAP (Assemble Species by Automatic Partitioning;
ASAP was applied to our COI alignment using the ASAP webserver available at https://bioinfo.mnhn.fr/abi/public/asap/asapweb.html, computing the genetic distances under the Kimura 2-parameter substitution model (K2P;
MZL Musée de Zoologie Lausanne (Switzerland);
LESCB Laboratoire Ecologie, Systématique, Conservation de la Biodiversité, Tétouan (Morocco).
Larva. Following combination of characters: A) labrum with anterior margin nearly straight; ratio width vs. length ca. 1.6× (Fig.
Larva (Figs
Colouration
(Fig.
Labrum
(Fig.
Right mandible
(Fig.
Left mandible
(Fig.
Hypopharynx and superlinguae
(Fig.
Maxilla
(Fig.
Labium
(Fig.
Hind protoptera well developed.
Foreleg
(Fig.
Terga
(Figs
Sterna. Posterior margin of sterna I–VI smooth, without spines. Posterior margin of sterna VII–VIII with small, triangular spines.
Tergalii
(Figs
Paraproct
(Fig.
Caudalii
(Fig.
Subimago. Judging from subimaginal tarsomeres developing under cuticle of last instar female larvae, all tarsomeres of all legs of female subimago have pointed microlepids on surface (see
Imago. Unknown.
Dedicated to Prof. Boudjéma Samraoui, committed researcher on aquatic insects in Algeria, and collector of the new species; in recognition to his substantial contribution to the knowledge of the ecology and distribution of Algerian mayflies.
Centroptilum samraouii sp. nov. occupies the headwaters of steep, narrow and intermittent streams (Fig.
(Fig.
Holotype. Algeria • larva; Guitna sup., Ghora; 36°36'42"N, 08°21'19"E; 22.01.2020; leg. B. Samraoui; on slides; GBIFCH00592552, GBIFCH00592551, GBIFCH00592622; MZL. Paratypes. Algeria • 2 larvae; Guitna sup., Ghora; 36°36'42"N, 08°21'19"E; 05.11.2019; leg. B. Samraoui; on slides; GBIFCH00895417, GBIFCH00895418; MZL • 3 larvae; Guitna sup.; 36°36'42"N, 08°21'19"E; 09.10.2019; leg. B. Samraoui; on slide; GBIFCH00592553; 2 in alcohol; GBIFCH00975620, GBIFCH00975623; MZL • larva; Louar inf., Ghora; 36°37'03"N, 08°22'49"E; 05.11.2019; leg. B. Samraoui; on slide; GBIFCH00592555; MZL • larva; Algeria; Guitna inf.; 07.11.2018; leg. B. Samraoui; in alcohol; GBIFCH00975621; MZL.
Larva. Following combination of characters: A) labrum with anterior margin slightly concave; ratio width vs. length ca. 1.5× (Fig.
Centroptilum alamiae sp. nov., larva morphology a labrum (left: ventral view; right: dorsal view) b right mandible c right prostheca d left mandible e left prostheca f hypopharynx and superlinguae g maxilla h glossa and paraglossa (ventral view) i glossa and paraglossa (ventral view) j glossa and paraglossa (dorsal view) k labial palp (left: ventral view; right: dorsal view).
Larva (Figs
Colouration
(Fig.
Labrum
(Fig.
Right mandible
(Fig.
Left mandible
(Fig.
Hypopharynx and superlinguae
(Fig.
Maxilla
(Fig.
Labium
(Fig.
Hind protoptera well developed.
Foreleg
(Fig.
Terga
(Figs
Sterna. Posterior margin of sterna I–VI smooth, without spines. Posterior margin of sterna VII–VIII with small, triangular spines.
Tergalii
(Figs
Paraproct
(Fig.
Caudalii
(Fig.
Subimago. Judging from subimaginal tarsomeres developing under cuticle of last instar female larvae, all tarsomeres of all legs of female subimago have pointed microlepids on surface (see
Imago. Unknown.
Dedicated to Prof. Majida El Alami, committed researcher on aquatic insects in Morocco, and collector of some of the specimens; in recognition of her substantial contribution to the knowledge of the systematics, ecology, and distribution of Moroccan mayflies.
The specimens were collected in calm edge waters, loose substrate, low to moderate current, high temperatures, and sites rich in filamentous algae and mosses (Fig.
(Fig.
Holotype. Morocco • larva; Oued Kelâa, Akchour; 35°14'32"N, 05°10'10"W; 13.03.2021; leg. S. El Yaagoubi; on slide; GBIFCH00592619, GBIFCH00592620, GBIFCH00592621; MZL. Paratypes. Morocco • 6 larvae; same data as holotype; 2 on slides; GBIFCH00980875, GBIFCH00980876; 4 in alcohol; GBIFCH00975645, GBIFCH00975646; MZL • 7 larvae; Oued Jnane Niche (sup.); 16.03.2014; leg. M. El Alami; in alcohol; GBIFCH00975647; MZL • 12 larvae; Oued Jnane Niche (sup.); 17.05.2015; leg. M. El Alami; 1 on slide; 11 in alcohol; LESCB.
The COI ingroup data set was 98% complete and included 34% of parsimony informative sites. The missing data almost exclusively resulted from nine GenBank sequences that lacked 5’ and/or 3’ end. All main CO1 gene tree relationships were resolved and well supported, except for the placement of the three clades Centroptilum sp. 1, C. sp. 2, and C. luteolum 1 (Fig.
Bayesian majority-rule consensus tree reconstructed from the CO1 data set. Coloured vertical boxes indicate species delimitation hypothesis according to the ASAP, GMYC and mPTP methods. Tips labelled with GBIF codes indicate newly sequenced specimens, CH007_SR codes designate sequences from the FREDIE project, and other codes correspond to previously published GenBank sequences. For each mPTP species hypothesis, the corresponding species names (where available) and the country of origin is provided. Circles on branches indicate Bayesian posterior probabilities > 0.95. Outgroup branches, tips labels, and species names are presented in grey.
The characters differentiating the geographically relatively close species Centroptilum luteolum, C. samraouii sp. nov. and C. alamiae sp. nov. are summarised in Table
Differentiating characters of new species of Centroptilum and C. luteolum (Switzerland, VD, Le Chenit, 18 Aug 2001, leg. A. Wagner) (M: 11B and M: 11F refer to figures in
Characters | No. in |
C. luteolum | Figs | C. samraouii sp. nov. | Figs | C. alamiae sp. nov. | Figs |
---|---|---|---|---|---|---|---|
Larva | |||||||
Head, mouthparts | |||||||
Labrum, width/length ratio | II.1 | 1.4–1.6 | ca. 1.6 | 1a | ca. 1.5 | 7a | |
Labrum, anterior margin | II.3 | nearly straight, medial emargination angular | nearly straight, medial emargination angular | 1a | slightly concave, medial emargination angular | 7a | |
Maxillary palp, segment III | II.5 | (bluntly) pointed apex | pointed apex | 1g | bluntly pointed/rounded apex | 7g | |
ca. 1.2× as long as segment II | ca. 1.3× as long as segment II | ca. 1.6× as long as segment II | |||||
Maxillary palp, length | ca. 1.8× as long as galea-lacinia | ca. 1.9× as long as galea-lacinia | 1g | ca. 1.7× as long as galea-lacinia | 7g | ||
Rhight mandible, denticles | II.6 | 3 + 2 | 3 + 2 | 1b | 3 + 2 | 7b | |
Left mandible, denticles | II.7 | 4 + 2 (rarely 4 + 3) | 4 + 3 | 1d | 4 + 3 | 7d | |
Labial palp segment III | II.12 | Distal (inner) margin concave | Distal (inner) margin concave | 1j | Distal (inner) margin slightly concave | 7k | |
Thorax, legs | |||||||
Legs, colour pattern | III.4 | femur with brown band distally; tibia proximally darker | legs light brown; claw darker | 3b | femur distomedially darker, tarsus basally and distally darker; claw basally darker | 9a–c | |
Fore femur, dorsal margin | III.6 | occasional short, pointed setae on margin | occasional short, pointed setae on margin | 2a | occasional short, pointed setae on margin; row of short, pointed, setae near margin | 8a | |
Fore tibia, length vs. tarsus | ca. equal length | slightly longer (ca. 1.1×) | 2a | ca. equal length | 7a | ||
Abdomen | |||||||
Terga, posterior margin (spines) | IV.5, 6 | I: no spines | I: no spines | I: no spines | |||
II–IX: long, narrow triangular, pointed | 4c, f | II–III: small triangular | 4a, d | II–VI (VII): small triangular | 4b, e | ||
5c | IV–IX: medium triangular | 5a | VII–IX: medium triangular | 5b | |||
Terga VII–IX, posterolateral part | IV.7 | VII: no spines | VII: no spines | VII: no spines | |||
VIII: ca. 3 spines | VIII: ca. 5 spines | VIII: ca. 4 spines | |||||
IX: 10–13 spines | IX: ca. 8 spines | IX: ca. 12 spines | |||||
Sterna, posterior margin (spines) | IV.10 | I–IV: no spines | I–VI: no spines | I–V: no spines | |||
V: rudimentary spines | VII–IX: very small triangular | VI: rudimentary | |||||
VI–IX: medium triangular | VII–IX: very small triangular | ||||||
Paraproct, distal margin | IV.14 | 23–30 pointed spines | M: 11B | 17–23 pointed spines | 2j | 30–45 pointed spines | 7j |
plus some spines in 2nd row | plus few smaller in 2nd row | partly split tips | |||||
plus few in 2nd row | |||||||
Caudalii, posterior margin of segments (spines) | IV.17 | elongated, triangular spines | M: 11F | elongated, triangular spines | 2k | triangular spines with | 8k |
with long points | short points |
The recently described species C. volodymyri (Georgia, Turkey, Iran) differs from C. samraouii sp. nov. and C. alamiae sp. nov. by several distinct characters: maxillary palp much longer than galea-lacinia (ca. 2.3×); maxillary palp segment I distinctly wider than segment II (only slightly wider in all other species); labrum much wider than long (1.8–2.0×); claw with more than 60 minute denticles in two rows (ca. 30 per row) (
The poorly known species C. pirinense (Pirin Mountains, Bulgaria) differs from C. samraouii sp. nov. and C. alamiae sp. nov. at least in the very wide labrum (ca. 2.0× wider than long;
Judging from tarsomeres of subimagos developing under cuticle of female last instar larvae, at least female subimagos of both new species of Centroptilum have all their tarsomeres of all legs covered with pointed microlepids. This is in line with C. luteolum, which has pointed microlepids on all tarsomeres of all legs of male and female subimagos (
The two new North African species described here are highly supported by our CO1-based analyses. First, the minimum mean genetic distance of 9.2% (mean distance between Centroptilum alamiae sp. nov. to C. luteolum 1) is much higher than the generally accepted intra-/interspecific threshold value of ca. 3% divergence for mayflies (e.g.,
We are very thankful to André Wagner (Museum of Zoology Lausanne) for the collection of Swiss material for comparison.
Furthermore, we are thankful to Michel Sartori (Museum of Zoology Lausanne) for his constant interest and support for our projects and to Céline Stoffel (Museum of Zoology Lausanne) for her support with lab work and preparation of the COI barcodes.
Lastly, the authors are grateful to the reviewers Roman J. Godunko and Pavel Sroka for their valuable recommendations and comments on the manuscript.