A review of Copelatus diving beetles from the Solomon Islands, reporting the discovery of six new species (Coleoptera, Dytiscidae, Copelatinae) Author Hajek, Jiri https://orcid.org/0000-0001-5779-1542 Department of Entomology, National Museum, Cirkusova 1740, CZ- 193 00, Prague 9 - Horni Pocernice, Czech Republic jiri.hajek@nm.cz Author Shaverdo, Helena Naturhistorisches Museum Wien, Burgring 7, 1010, Vienna, Austria Author Hendrich, Lars SNSB-Zoologische Staatssammlung Muenchen, Muenchhausenstrasse 21, D- 81247, Munich, Germany Author Balke, Michael https://orcid.org/0000-0002-3773-6586 SNSB-Zoologische Staatssammlung Muenchen, Muenchhausenstrasse 21, D- 81247, Munich, Germany & GeoBioCenter, Ludwig-Maximilians-University, Munich, Germany text ZooKeys 2021 2021-03-10 1023 81 118 http://dx.doi.org/10.3897/zookeys.1023.61478 journal article http://dx.doi.org/10.3897/zookeys.1023.61478 1313-2970-1023-81 F14F12AC47824643929A49941E24BB92 8E4EE48C84345AC48B877220002D94B6 Copelatus urceolus sp. nov. Figures 9 , 21 Type locality. Solomon Islands , Guadalcanal , Vulavula River . Type material. Holotype : , labelled: " [p] // Type [round label with red frame, p] // SOLOMON IS: / GUADALCANAL / 1720' 6.viii.53. [hw] // Small pool on top / of large boulder in Vulavula River . [hw] // Brit.Mus. / 1987-14 [p] // aD 2 [hw] // Copelatus / Copelatus urceolus Type! [hw] / J. Balfour-Browne det., 195 [p] 3 [hw]" ( NHMUK ) . Description of male holotype . Habitus : Elongate, oblong-oval, broadest before mid-length of elytra; body distinctly convex in lateral view. Body outline continuous, without discontinuity between pronotum and elytra. Dorsal surface shiny (Fig. 9 ). Figures 9-12. Habitus of Copelatus 9 C. urceolus sp. nov. ( holotype , TL: 5.1 mm ) 10 C. variistriatus sp. nov. ( holotype ; TL: 6.6 mm ) 11 C. variistriatus sp. nov. (male paratype with reduced striae; TL: 6.2 mm ) 12 C. variistriatus sp. nov. (striolate female paratype ; TL: 5.9 mm ). Colouration : Head, lateral parts of pronotum, appendages and prosternum orange-ferruginous; elytra, meso- and metaventrite, and abdomen pitchy brown; anterior margin and midpart of pronotum darkest, brown. Head : Moderately broad, ca. 0.60 x width of pronotum, trapezoidal. Anterior margin of clypeus indistinctly concave. Antenna with antennomeres long and slender. Reticulation consisting of moderately deeply impressed isodiametric meshes. Punctation double, consisting of coarse setigerous punctures, and very small punctures spread sparsely on surface; row of coarse punctures present around inner margin of eyes, few punctures present at frontal level of eyes, and several punctures anterolaterally to eyes in fronto-clypeal depressions. Pronotum : Transverse (width/length ratio = 2.48), broadest between posterior angles, lateral margins moderately curved. Sides with lateral beading thin, but distinct except for anterior angles. Reticulation similar to that of head. Punctation similar to that of head; rows of coarse setigerous punctures present along anterior margin, laterally in longitudinal depression close to sides, several punctures present also in basolateral depressions along basal margin. Centre of disc with medial longitudinal smooth line. Elytra : Base of elytra as broad as pronotal base; lateral margins of elytra curved, distinctly narrowing in apical half. Elytral striae absent. Reticulation similar to that of head and pronotum. Punctation consisting of coarse setigerous punctures and very fine sparse punctures. Coarse punctures arranged in three distinct longitudinal puncture lines: two discal and lateral; another row of punctures present along lateral margin of elytra, and few coarse punctures present also in interspace between discal and lateral puncture lines. Legs : Protibia modified, angled near base, distinctly broadened anteriorly, club shaped. Pro- and mesotarsomeres 1-3 distinctly broadened, with adhesive setae on their ventral side. Ventral side : Prosternum sinuate anteriorly, obtusely keeled medially. Prosternal process shortly lanceolate, in cross-section convex, apex obtuse; process distinctly bordered; reticulation almost effaced. Metaventrite with microsculpture consisting of polygonal meshes; lateral parts of metaventrite ("metasternal wings") tongue-shaped, slender. Metacoxal lines nearly complete, absent only very close to metaventrite. Metacoxal plates covered laterally with long, deep longitudinal strioles; reticulation consisting of extremely elongated, longitudinal polygonal meshes. Metacoxal processes rounded and incised at posterior margin. Abdominal ventrites I-II with longitudinal strioles. Tuft of setae present antero-medially on ventrites III-V; ventrite VI with setigerous punctures laterally on either side. Abdominal reticulation consisting of elongate polygonal meshes, longitudinal on ventrites I and II, oblique on ventrite III, and transverse on ventrites IV-VI. Punctation consisting of fine, sparsely distributed punctures. Genitalia : Median lobe of aedeagus (Fig. 21 ) sickle-shaped, with evident dorsal and ventral sclerites; dorsal sclerite without surface sculpture and divided into two parts in apical half: left part distinctly shorter than right one, parts slightly curved, with crests and broadly pointed apexes (Fig. 21A, B ); ventral sclerite divided into two parts apically: left part sclerotised, broader, shorter, with broadly pointed apex, right part longer, partly sclerotised (apically membranous), asymmetrically concave, with long, thin, rounded apex (Fig. 21C ). Lateral lobes (parameres) of narrow triangular form, with broader subdistal part due to curved setigerous dorsal margin; setae numerous, dense, and strong distally, and distinctly less numerous, weaker, and sparser basally (Fig. 21D ). Female. Unknown. Measurements. TL: 5.1 mm . TL-h: 4.5 mm . MW : 2.5 mm . Differential diagnosis. Member of the Copelatus hydroporoides species group, see under C. laevipennis sp. nov. Copelatus urceolus sp. nov. is most likely related to C. laevipennis sp. nov. and C. variistriatus sp. nov. It differs from both mentioned species in smaller body length, different shape of median lobe of male genitalia (cf. Figs 19 , 21 , 22 ), and from the latter species also in absence of elytral striae. Etymology. We adopted the manuscript name used by J. Balfour-Browne. Latin noun Copelatus urceolus (- i , masculinum) means small pitcher or jug, referring probably to the habitat in which the type specimen was caught; the name is used in the nominative case, standing in apposition. Distribution. The species is known only from the type locality in central Guadalcanal .