Berosus muellerorum, Seidel & Sýkora & Leschen & Fikáček, 2021

Seidel, Matthias, Sýkora, Vít, Leschen, Richard A. B. & Fikáček, Martin, 2021, A review of the New Zealand Berosus (Coleoptera: Hydrophilidae) with descriptions of three new species, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 61 (1), pp. 243-252 : 249-251

Berosus muellerorum sp. nov.

( Figs 1C, G ; 2B, G )

Type material. Hඈඅඈඍඒඉൾ: J ( NZAC), “NEW ZEALAND: GB, / Gisborne, Mangaone Road, W / of Route 2, Mangaone Stream, / -38.97138, 177.67152, 256m, / 18.i.2017, Leschen & Maier / leg., water collecting, NZ17-0118-CM3 // DNA isolate:/ NZ635.1 / extracted by M.Seidel 2017 / DNA extract deposited in / Natural Museum, Prague // HOLOTYPE / Berosus muellerorum / n. sp. / Seidel et al. 2019”. Pൺඋൺඍඒඉൾඌ: NEW ZEALAND: NඈඋඍΗ Iඌඅൺඇൽ: Hawkes Bay: 1 ♀ ( FMNH): same data as holotype; 3 JJ 2♀♀ ( NZAC, FMNH, NMPC):Putorino, nr.On Route 2, Waikiri River, 39.12945°S, 176.9974°E, 36 m, 20.i.2017, water collecting, Leschen & Maier lgt.; 2 ♀♀ ( EMEC, NMPC): Hwy 2 McIntyre Acc. Rd., 39°15.18′S 176°52.76′S, 69 m, 21.ii.2016, William D. Shepard leg., WDS-A-2005. Gisborne: 3 ♀♀, 3 spec. ( NZAC, NMPC, DZRJ, DZUP): Te Urewera NP, Papakorito Falls, 1.4 km NEE of Aniwaniwa, 650 m, 25.xi.2012, 38°44.4′S 177°10.6′E, in semipermament/permanent puddles on the road at the beginning of Aniwaniwa track, Becker, Fikáček, Hájek, NZ14; 2 ♀♀ ( NZAC):Waimata Valley Road,Waimata River, 38.53309°S,

178.03939°E, 50 m, 21.i.2017, water collecting, Leschen & Maier leg., NZ 17-0121-CM2; 1 ♀ ( NMPC): Te Urewera NP, Lake Waikaremoana Motorcamp, 600 m, 22.–26.xi.2012, 38°45.3′S 177°9.4′E, exposed, muddy puddles at the side of the road, Becker, Fikáček, Hájek lgt.; 1 spec. ( EMEC): Waikohu River at Hwy. 2, just S Rakauroa, -38.41521, 177.56088, 21.ii.2016, C. B. Barr lgt. Wanganui: 3 ♀♀ ( NZAC, EMEC): Bulls, 40°11.17′S 175°23.47′E, 9.ii.2016, 33 m, pools near river,William D. Shepard. lgt., WDS-A-1988A.

Additional material examined. Larvae. 1 third instar larva ( NMPC): Putorino, nr. On Route 2, Waikiri River, 39.12945°S, 176.9974°E, 36 m, 20.i.2017, water collecting, Leschen & Maier lgt.

Description of adults [characters identical to B. pallidipennis description are not repeated]. Body length 4.4–5.4 mm (holotype: body length: 4.7 mm; humeral width: 1.8 mm). Shape elongate ellipsoid ( Figs 2C, G ).

Coloration. Pronotum with yellowish ground color and dark metallic central spot which is narrowly rectangular in anterior half and widely semicircular posteriorly. Maxillary palpi with palpomere 4 darkened in apical fourth. Legs with black trochanters, remaining parts testaceous.

Dorsum. Pronotal surface with long pale decumbent setae. Surface of elytra smooth in males, with mesh-like microsculpture in females. Elytral apices divergent and pointed in males, divergent and rounded in females, in both sexes leaving a wide gap between apices when elytra are closed.

Ventrum. Mesoventrite with low pubescent median ridge not projecting into a process posteriorly. Abdominal ventrite 5 with a narrow very shallow notch in males, and a wide and slightly deeper apical notch in females.

Legs. Male protarsus with adhesive soles on tarsomere 1, which is ca. three-times as thick as following tarsomeres; tarsomere 4 slightly longer than tarsomeres 1–3 combined.

Male genitalia. Total length 2.13 mm. Parameres long, narrow, gradually acuminate, apical half straight and pointing ventrally in lateral view. In dorsal view the parameres curving in towards each other, apices pointed. Median lobe much shorter than parameres, very narrow.

Larval morphology ( Figs 1I–J ). Larva corresponds to the larvae of other species of Berosus in the main characteristics (head with large left and minute right epistomal lobe, mandibles of the ‘ Berosus -typeʼ, labium reduced in size, ligula absent, abdomen with one pair of tubular spiracular gills on sides of segments I–VIII, spiracular system closed, spiracular atrium absent; Mංඇඈඌπංආൺ & Hൺඒൺඌπං 2015, Fංκගඹൾκ et al. 2018). In contrast to the known larvae, the body is very wide and robust, with large laterodorsal tubercles above the bases of tracheal gills. The head differs from all known Berosus larvae in the absence of a nasale: anteromedian margin of head is completely smooth ( Fig. 1J ).

Differential diagnosis. Berosus muellerorum sp. nov. differs from B. pallidipennis and B. maru sp. nov. by the pronotal spot narrowing anteriorly; in this character it resembles B. halasi sp. nov. from which it differs by the male genitalia and a wider and shallower emargination of the abdominal apex in females.

Etymology. The species is named after Swiss naturalist Roland A. Müller (see obituary by Hඟආඟඅඟංඇൾඇ & Tඈඅ 2017) and his wife Anna-Maija Müller Kaltula (St. Gallen, Switzerland). The name is a noun in genitive plural case.

Habitat. This species was collected in pools along rivers and streams as well on temporary pools on roads in open landscape.

Distribution ( Fig. 3C ). Southern and eastern part of North Island (Wanganui, Gisborne, Hawkes Bay).

Figures

Fig. 1. External morphology of New Zealand Berosus, adults and larvae.A, E – B. pallidipennis (Sharp, 1884); B, F – B. maru sp. nov.; C–G, I–J, L – B. muellerorum sp. nov.; D–H, K – B. halasi sp. nov.; A–H – dorsal views; K–L – elytral apices; I–J – third instar larva (I – dorsal, semilateral and lateral view; J – head in dorsal view).

Fig. 2. New Zealand Berosus, details of adult morphology. A–D – coloration of meso- and metafemora; E–I – aedeagus in dorsal, lateral and ventral view; E–F – B. pallidipennis (Sharp, 1884) from North and South Island; G – B. muellerorum sp. nov.; H – B. halasi sp. nov.; I – B. maru sp. nov. The inset in grey: relative size of male genitalia of all species.

Fig. 3. Distribution and habitats of Berosus in New Zealand. A–D. Maps of examined specimens. E–H. Habitat photos of collection sited. E – shore of Lake Roundabout in Mid Canterbury, type locality of B. halasi sp. nov.; F – isolated rocky pools along Boyle River at Windy Point in North Canterbury, type locality of B. maru sp. nov.; G – pool at Wanaka Mount Aspiring Road in Otago Lakes, locality of B. pallidipennis (Sharp, 1884); H – exposed puddles in riverbed of Kahutara River at Inland Kaikoura Road in Kaikoura, locality of B. pallidipennis.