An Update of the Hydraena Fauna of the Comoro Islands (Indian Ocean), with Description of H

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Zeitschrift/Journal: Koleopterologische Rundschau

Jahr/Year: 2016

Band/Volume: 86_2016

Autor(en)/Author(s): Jäch Manfred A., Diaz Juan Angel

Artikel/Article: An update of the Hydraena fauna of the Comoro Islands (Indian Ocean), with description of H. (Hydraenopsis) maryae sp.n. from Mayotte 91-96 ©Wiener Coleopterologenverein (WCV), download unter www.zobodat.at

Koleopterologische Rundschau 86 91–96 Wien, September 2016

JÄCH, M.A. & BALKE, M. (eds.) 2010: Water beetles of New An update of the Hydraena fauna of the Comoro Islands Caledonia (part 1). – Monographs on Coleoptera 3: IV+449 pp. (Indian Ocean), with description of The uniqueness of the fauna and H. (Hydraenopsis) maryae sp.n. from Mayotte flora of New Caledonia is vir- tually unparalleled. No other re- (Coleoptera: Hydraenidae) gion in the world for example en- compasses a similarly high floral M.A. JÄCH & J.A. DELGADO endemism in relation to its land coverage! Abstract The WATER BEETLES OF NEW Hydraena maryae sp.n. (Coleoptera: Hydraenidae) is described from Mayotte (Comoro Islands, Indian CALEDONIA in the past have been Ocean). Hydraena borbonica ofella BALFOUR-BROWNE, 1958 is elevated to species level. studied very poorly. In the second half of the 20th century only five Key words: Coleoptera, Hydraenidae, Hydraena, new species, Mayotte, Comoro Islands, Indian new species of water beetles have Ocean. been described from this Archi- pelago. Introduction Volume 3 of the Monographs on The Comoro Islands or Comoros form an archipelago of volcanic islands situated off the south- Coleoptera is entirely dedicated east coast of Africa, to the east of Mozambique and north-west of Madagascar. Geologically, to the Water Beetles of New Cale- Maore (or Grande-Terre; Department of Mayotte, France) is the oldest of the Comoro Islands. donia. Based mainly on two field So far, only one species of Hydraenidae, Hydraena borbonica FAIRMAIRE, 1898 (originally surveys carried out by the editors, described from La Réunion), has been recorded from the Comoros. BALFOUR-BROWNE (1958) Manfred A. Jäch and Michael described a new subspecies (Hydraena borbonica ofella BALFOUR-BROWNE, 1958) based on Balke in 2001 and 2009, the these specimens from the Comoro Islands. knowledge of the Water Beetles of New Caledonia is updated. In the course of a hydrobiological survey, Nathalie Mary (Tahiti, French Polynesia) managed to collect a second species of Hydraena KUGELANN, 1794 in the Comoro Islands. The description This book includes 23 taxo- of this species is presented herein, together with taxonomic-nomenclatural notes on Hydraena nomic/faunistic papers authored borbonica ofella. by 19 experts from 12 countries. A total of 58 new species (Dytisc- idae: 28, Hydrophilidae: 17, Scirtidae: 12, Limnichidae: 1) is described from New Caledonia, all Hydraena (Hydraenopsis) maryae sp.n. of them being endemic! In addition, six species are described from other Indo-Pacific Islands TYPE LOCALITY (Fig. 5): Lower course of Djalimou, east of Kani-Kéli, 12°57'14.4''S (Bacan, Ceram, Fiji, New Guinea, Wallis & Futuna). Four genera and seven species are newly 45°06'51.7''E, 15 m a.s.l., southern Maoré Island (= Mahoré or Grande Terre), Mayotte, Comoro recorded from New Caledonia in this volume. One endemic species, Berosus distigma Fauvel Islands. (Hydrophilidae), has not been collected since more than a hundred years and it is therefore regarded as extinct. Several other species are threatened with extinction. TYPE MATERIAL: Holotype  (Naturhistorisches Museum Wien, Austria): “COMOROS Mayotte, Djalimou aval 30.VIII.2013 leg. N. Mary”. This book is richly illustrated. It includes 161 excellent color photographs (98 beetles, 63 habitat pictures). Furthermore, distribution maps are provided for all 124 New Caledonian species DESCRIPTION (male): Habitus as in Fig. 1. Body length: 1.48 mm. Dorsum yellowish to treated. reddish brown, lateral parts of frons (near eyes) black, lateral parts of clypeus, anterior, posterior and lateral sides of pronotum paler yellowish brown; maxillary palpi yellowish, apical tip paled. Orders should be sent to: [email protected] or Labrum deeply excised anteriorly; lobes rounded anteriorly, without corners. Clypeus sparsely [email protected] irregularly micropunctate, matt. Fronto-clypeal suture very feebly arcuate, slightly impressed. Price: 40 € (for members of Vienna Coleopterists Society, 60 € for non-members) Frons sparsely (middle) to moderately densely (laterally) punctate, interstices shining; inter- The contents of this book are listed on page 280. ocular grooves more or less obsolete. Eyes large, protruding, more than 30 facets visible in dorsal view. http://www.coleoptera.at/monographs_on_coleoptera.php

©Wiener Coleopterologenverein (WCV), download unter www.zobodat.at 92 Koleopt. Rdsch. 86 (2016)

Fig. 1: Habitus of Hydraena maryae, holotype. ©Wiener Coleopterologenverein (WCV), download unter www.zobodat.at

92 Koleopt. Rdsch. 86 (2016) JÄCH & DELGADO: Update of the Hydraena fauna of the Comoro Islands (Indian Ocean) (HYDRAENIDAE) 93

Figs. 2–4: Hydraena maryae, 2) aedeagus in a) dorsal view, b) ventral view (setae of right paramere Fig. 1: Habitus of Hydraena maryae, holotype. shown in inset) and c) lateral view, 3) terminal sternite and spiculum, 4) male tergite X. Scales: 0.1 mm. ©Wiener Coleopterologenverein (WCV), download unter www.zobodat.at 94 Koleopt. Rdsch. 86 (2016)

Pronotum wider than long, widest near middle; anterior margin concave; anterior angles sub- acute, almost rounded; lateral rim slightly denticulate; disc rather flat, moderately densely punctate, glabrous, foveae more or less obsolete; anterior and posterior portions of pronotum more densely punctate. Elytra subparallel-sided; with about nine rows of punctures between suture and shoulder; punctures moderately large, moderately deeply impressed, arranged in almost regular, not impressed lines; intervals and interstices flat and glabrous; explanate margin of elytra moderately wide, not serrate posteriorly. Elytral apices separately rounded. Foretibia very slightly curved; medial margin of hind tibia distinctly dilated from base to middle, then slightly concave toward apex. Mesoventral process slightly narrower than mesotibia, parallel-sided, apically truncate. Metaventrite moderately deeply impressed between glabrous metaventral plaques. Male terminal sternite and spiculum (Fig. 3) and male tergite X (Fig. 4) strongly asymmetrical, the latter with a conspicuous subapical cavity. Aedeagus (Fig. 2a–c): Main piece strongly asymmetrical in ventral view, somewhat angulate before middle, with a single subapical dorsal seta, near the base with an acute projection pointing to right side; phallobase asymmetrical, closed proximally. Distal lobe quite large, intricately shaped, with a moderately long, flagellum-like appendage. Right paramere long and slender, articulately connected with main piece, inserted before middle; with a very dense subapical brush of short setae on median face, and with six long setae at apex and subapical ventral margin. Left paramere very short, not articulately connected with main piece, inserted after middle, with a few moderately long setae. HABITAT: Fig. 5. DISTRIBUTION: Known only from the type locality. ETYMOLOGY: This species is named for Nathalie Mary (Tahiti, French Polynesia), who collected the holotype.

Hydraena (Hydraenopsis) ofella BALFOUR-BROWNE, 1958 Hydraena borbonica ofella BALFOUR-BROWNE 1958: 138. – BAMEUL 1986: 877. Hydraena (s.str.) borbonica ofella BALFOUR-BROWNE: HANSEN 1998: 38. BALFOUR-BROWNE (1958) described this taxon after specimens collected near Dzaoudzi (type locality) on the island of Pamanzi (very close to Maoré, the main island of Mayotte; Department of Mayotte, France) and from Mohéli (Union of the Comoros). Since then, it has never been collected again. The aedeagi of Hydraena borbonica borbonica and H. borbonica ofella were illustrated by BALFOUR-BROWNE (1958: fig. 2). They are sufficiently different to allow the conclusion that H. borbonica (so far known only from La Réunion) and H. ofella are indeed two discrete species. DISTRIBUTION: So far known only from two islands in the Comoros: Mohéli, Pamanzi (= Petite Terre).

Discussion Hydraena maryae is the second species of Hydraenidae recorded from the Comoro Islands, and the first one recorded from Maoré, the main island of the Department of Mayotte, France. It does not appear to be particularly closely related with any other described species of Hydraena ©Wiener Coleopterologenverein (WCV), download unter www.zobodat.at

94 Koleopt. Rdsch. 86 (2016) JÄCH & DELGADO: Update of the Hydraena fauna of the Comoro Islands (Indian Ocean) (HYDRAENIDAE) 95

Pronotum wider than long, widest near middle; anterior margin concave; anterior angles sub- described so far. However, it is obviously very closely related with an undescribed species from acute, almost rounded; lateral rim slightly denticulate; disc rather flat, moderately densely northern Madagascar (P. Perkins, pers. comm.). The species known from the Seychelles (see punctate, glabrous, foveae more or less obsolete; anterior and posterior portions of pronotum JÄCH & DELGADO in press) and the Mascarene Islands (see BAMEUL 1986, JÄCH & BROJER 2012) more densely punctate. are all quite different. Elytra subparallel-sided; with about nine rows of punctures between suture and shoulder; Remarkably, the genus Hydraena has not yet been recorded from the two largest islands of the punctures moderately large, moderately deeply impressed, arranged in almost regular, not Comoro Archipelago: Grande Comore and Anjuan. impressed lines; intervals and interstices flat and glabrous; explanate margin of elytra moderately wide, not serrate posteriorly. Elytral apices separately rounded. Foretibia very slightly curved; medial margin of hind tibia distinctly dilated from base to middle, then slightly concave toward apex.

Mesoventral process slightly narrower than mesotibia, parallel-sided, apically truncate. Metaventrite moderately deeply impressed between glabrous metaventral plaques.

Male terminal sternite and spiculum (Fig. 3) and male tergite X (Fig. 4) strongly asymmetrical, the latter with a conspicuous subapical cavity. Aedeagus (Fig. 2a–c): Main piece strongly asymmetrical in ventral view, somewhat angulate before middle, with a single subapical dorsal seta, near the base with an acute projection pointing to right side; phallobase asymmetrical, closed proximally. Distal lobe quite large, intricately shaped, with a moderately long, flagellum-like appendage. Right paramere long and slender, articulately connected with main piece, inserted before middle; with a very dense subapical brush of short setae on median face, and with six long setae at apex and subapical ventral margin. Left paramere very short, not articulately connected with main piece, inserted after middle, with a few moderately long setae. HABITAT: Fig. 5. DISTRIBUTION: Known only from the type locality.

ETYMOLOGY: This species is named for Nathalie Mary (Tahiti, French Polynesia), who collected the holotype.

The aedeagi of Hydraena borbonica borbonica and H. borbonica ofella were illustrated by BALFOUR-BROWNE (1958: fig. 2). They are sufficiently different to allow the conclusion that H. borbonica (so far known only from La Réunion) and H. ofella are indeed two discrete species.

DISTRIBUTION: So far known only from two islands in the Comoros: Mohéli, Pamanzi (= Petite Terre).

Discussion

Hydraena maryae is the second species of Hydraenidae recorded from the Comoro Islands, and the first one recorded from Maoré, the main island of the Department of Mayotte, France. It does not appear to be particularly closely related with any other described species of Hydraena Fig. 5: Type locality of Hydraena maryae. ©Wiener Coleopterologenverein (WCV), download unter www.zobodat.at 96 Koleopt. Rdsch. 86 (2016)

Acknowledgements We are most grateful to Nathalie Mary (Tahiti, French Polynesia) for sending the single speci- men of the new species from Mayotte.

References BALFOUR-BROWNE, J. 1958: New species of Malgassic Hydrophilidae [Col.]. – The Mauritius Institute Bulletin V (4): 134–147. BAMEUL, F. 1986: Les Hydrophiloidea des îles Mascareignes (Coleoptera). – Revue suisse de Zoologie 93 (4): 875–910. HANSEN, M. 1998: Hydraenidae. – In Hansen, M. (ed.): World Catalogue of Insects 1. – Stenstrup: Apollo Books, 168 pp. JÄCH, M.A. & BROJER, M. 2012: Hydraena legorskyi sp.n. from Rodrigues (Mascarene Islands, Indian Ocean) (Coleoptera: Hydraenidae). – Koleopterologische Rundschau 82: 87–93. JÄCH, M.A. & DELGADO, J.A. in press: Hydraena Kugelann, 1794 (Coleoptera, Hydraenidae) from the Seychelles, Indian Ocean, with description of a new species. – Zookeys.

Dr. Manfred A. JÄCH Naturhistorisches Museum, Burgring 7, A – 1010 Wien, Austria ([email protected])

Dr. Juan A. DELGADO Departamento de Zoología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain ([email protected])