Research Article |
Corresponding author: Manfred A. Jäch ( manfred.jaech@nhm-wien.ac.at ) Academic editor: Mariano Michat
© 2016 Manfred A. Jäch, Juan A. Delgado.
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:
Jäch MA, Delgado JA (2016) Hydraena Kugelann, 1794 (Coleoptera, Hydraenidae) from the Seychelles, Indian Ocean, with description of a new species. ZooKeys 623: 75-88. https://doi.org/10.3897/zookeys.623.10052
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Hydraena matyoti sp. n. (Coleoptera, Hydraenidae) is described from the Seychelles, Indian Ocean. Hydraena mahensis Scott, 1913 is redescribed. The latter is here recorded from La Digue for the first time. A key to the species of the genus Hydraena Kugelann, 1794 of the Seychelles is presented.
Coleoptera , Hydraenidae , Hydraena , new species, Seychelles, Mahé, La Digue, Silhouette, Indian Ocean
So far, only one species of Hydraenidae, Hydraena mahensis Scott, 1913, has been recorded from the Seychelles (see
Line drawings were prepared with the aid of a camera lucida attached to a Nikon eclipse E600 microscope. Habitus photographs were taken with a Nikon DS-U2 unit Camera attached to a Leica MZ9S stereomicroscope. Images were stacked using CombineZP.
BMNH The Natural History Museum, London, UK
CDUM Coll. J.A. Delgado, University of Murcia, Spain
IBE Institute of Evolutionary Biology (Institut de Biologia Evolutiva), Barcelona, Spain
NMW Naturhistorisches Museum Wien, Austria
Hydraena
(s.str.)
mahensis
:
Hydraena
mahensis
:
Hydraena (Hydraenopsis) mahensis
:
Marshes of coastal plain at Anse aux Pins and Anse Royale, Mahé, Seychelles.
Two syntypes. One of these syntypes is deposited in the BMNH (M. Barclay, email, 22.VII.2016). It is labelled as “Holotype” (red edged disc) and as ‘Type’ (blue rectangle). The second syntype (“Mahe 146” [handwritten on the rear edge of the card carrying the beetle], “Mahe 1908-09 Seychelles Exp.” [printed], “Hydraena mahensis H. Scott Paratype.” [handwritten]) is deposited in the Cambridge University Museum (W. Foster, email, 7.IX.2016).
Mahé: 26 exs. (CDUM, NMW): Mahé (south), Petite Police Bay, swamp, 4°48.10'S 55°31.03'E, IX.2014, leg. M. Madl. La Digue: 1 ♂, 1 ♀ (NMW): La Réunion, ca. 5 m a.s.l., 7.IV.2007, leg. G. Wewalka (7).
The DNA of one female (voucher number IBE-AN186) was non-destructively extracted using the DNeasy Tissue Kit (Qiagen GmbH, Hilden, Germany) in the IBE. Two fragments of the cytochrome C oxydase subunit (COI) were sequenced, the 5’ end (the barcode fragment, primers LCO1490 and HCO2198,
Habitus as in Fig.
Labrum deeply excised anteriorly; lobes rounded anteriorly. Middle of clypeus very sparsely punctate and glabrous, lateral parts densely micropunctate and mat. Fronto-clypeal suture more or less straight, slightly impressed. Frons moderately densely punctate laterally, sparsely punctate medially, interstices shining; interocular grooves obsolete. Eyes large, protruding, more than 30 facets visible in dorsal view.
Pronotum wider than long, widest near middle; anterior margin weakly concave; anterior angles rounded; lateral rim denticulate; surface moderately densely punctate, but disc sometimes more sparsely punctate; discal foveae more or less obsolete.
Elytra elongately oval; with about nine rows of punctures between suture and shoulder; punctures small, not deeply impressed, arranged in almost regular, usually not impressed lines; intervals and interstices flat and glabrous; explanate margin of elytra only moderately wide, not strongly serrate posteriorly. Elytral apices usually separately rounded.
Foretibia very slightly curved in both sexes.
Mesoventral process parallel-sided, apically truncate, width sexually dimorphic. Metaventrite moderately deeply impressed in the middle; metaventral plaques rather indistinct, sometimes obscured by dense punctures.
Male terminal sternite and spiculum (Fig.
Aedeagus (Figs
Gonocoxite (Fig.
Female tergite X (Fig.
Spermatheca (Figs
Secondary sexual characters: Male mesoventral process more slender; in male more or less as wide as mesotibia, in female slightly wider than mesotibia.
Swamps and ditches in coastal plain. The swamp at Petite Police Bay (Fig.
This species is so far known only from Mahé (Anse aux Pins, Anse Royale, Petite Police Bay) and La Digue (La Réunion). It is here recorded from La Digue for the first time.
Hydraena (Hydraenopsis) mahensis : Jäch & Madl 2009: 19 (partim), 29.
Small puddle on Sans Souci Hiking Trail, northern Mahé, Seychelles.
Holotype ♂ (NMW), glued on pinned card, genitalia extracted and glued on same card. Label data: “SEYCHELLES: Mahé Sans Souci, XI. 1994, leg.E.Heiss”. Paratypes: 1 ♀ (NMW): same label data as holotype; 1 ♂ (NMW): “SEYCHELLES: Mahé Morne Seychellois NP Casse Dent, trail 25.03.2011 leg. M.Madl”; 2 ♀♀ (NMW): “SEYCHELLEN, Mahé 1996 Morne Seychellois NP Congo Rouge 600-800m 25. V. leg. Schödl (12c)”; 1 ♀ (NMW): “Seychelles, Silhouette, Jardin Marron [field name], 400m, 12. 4. 2007, leg. Wewalka (12)”.
Habitus as in Fig.
Labrum deeply excised anteriorly; anterior angles rounded. Middle of clypeus sparsely punctate, usually glabrous, lateral parts usually micropunctate and mat. Fronto-clypeal suture straight or feebly arcuate, slightly impressed. Frons moderately densely (middle) or more densely and sometimes even rugosely (laterally) punctate, interstices shining; interocular grooves shallow. Eyes large, protruding, more than 30 facets visible in dorsal view.
Pronotum distinctly wider than long, widest near middle; anterior margin concave; anterior angles rounded; lateral margin very slightly concave in anterior and posterior half; lateral rim denticulate; surface moderately densely to densely punctate, but disc sometimes only sparsely punctate; anterior discal foveae obsolete, posterior discal foveae hardly noticeable.
Elytra elongately oval; with about nine rows of punctures between suture and shoulder; punctures small, but rather deeply impressed, usually arranged in regular, usually not impressed lines; intervals sometimes convex, glabrous; explanate margin of elytra comparably wide, abruptly attenuate subapically, slightly to distinctly serrate posteriorly. Elytral apices usually separately rounded.
Foretibia and metatibia sexually dimorphic.
Mesoventral process parallel-sided, apically truncate, width sexually dimorphic. Metaventrite moderately deeply impressed between glabrous metaventral plaques, the latter reduced to very thin glabrous elevated short, widely separated streaks.
Male terminal sternite and spiculum (Fig.
Aedeagus (Figs
Gonocoxite (Fig.
Female tergite X (Fig.
Spermatheca (Figs
Secondary sexual characters: Foretibia and metatibia slightly curved in male. Male mesoventral process more slender; in male more or less as wide as mesotibia, in female slightly wider than mesotibia.
On Mahé this species was collected in a small puddle on a forest trail (leg. E. Heiss), and in small mountain streams at more than 600 m a.s.l. (leg. M. Madl and S. Schödl) – the single specimen collected by M. Madl was found on a small piece of wood lying in a very small stream (Fig.
Endemic to the Inner Seychelles. So far known only from Mahé and Silhouette.
This species is named for Pat Matyot, a Seychellois naturalist with a special interest in entomology. Pat Matyot is employed by the Seychelles Broadcasting Corporation and has produced many television features on the country’s fauna and flora. He has served on the boards and science committees of a number of conservation organisations in Seychelles and is at present a board member of the Island Conservation Society (ICS) and the Silhouette Foundation. The epithet is a noun in the genitive case.
1 | Body length (without abdomen): 1.20–1.40 mm. Frons without interocular depressions (Fig. |
mahensis |
– | Body length (without abdomen): 1.56–1.70 mm. Frons with shallow interocular depressions (Fig. |
matyoti |
The two Hydraena species of the Seychelles obviously live in different habitats. While H. mahensis is known only from lowland stagnant water, i.e., coastal swamps near the sea, the new species, H. matyoti, was collected only at higher elevations in the mountainous interior of the Seychelles Islands, i.e., in a small puddle, mountain streams, and in a seepage on a cliff. In suitable habitats, H. mahensis can be found in abundance, while H. matyoti seems to be generally very rare. In total, only six specimens were collected between 1994 and 2011 by four Austrian entomologists.
Although both species belong to the same subgenus they are not closely related and in fact they represent different species groups. Hydraena mahensis is very closely related to H. erythraea Régimbart, 1905 (H. erythraea group; “erythræa-phylum” sensu
We are most grateful to Ernst Heiss (Innsbruck, Austria), Günther Wewalka (Wien, Austria), and Michael Madl (Frauenkirchen, Austria) for donating their Hydraena specimens, which they collected in the Seychelles. The latter is also thanked for the habitat photographs. Special thanks are due to Max Barclay (BMNH) and William Foster (Cambridge University Museum) for information on the syntypes of Hydraena mahensis. We are grateful to Roger G. Booth (BMNH) for the examination of the syntype deposited in the BMNH. Pat Matyot is thanked for reading and correcting the manuscript. Ignacio Ribera and Anabela Cardoso (IBE) are thanked for sequencing Hydraena mahensis, and for submitting their data to GenBank.