Berosus maru, 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 : 248-249

Berosus maru sp. nov.

( Figs 1B, F, I–J ; 2C, I )

Type material. Hඈඅඈඍඒඉൾ: J ( NZAC), “NEW ZEALAND: N / Canterbury 22.8 km S of Lewis / Pass, Boyle River at Windy / Point; 515 m 42.58546°S, / 172.37549°E 8.xii.2016; / Fikáček & Seidel lgt. MM64 // in isolated rocky pools / with sandy bottom on the cliffs / above Boyle River next to / the hanging bridge // DNA isolate:/ NZ549.1 / extracted by M. Seidel 2016 / DNA extract deposited in / National Museum, Prague // HOLOTYPE / Berosus / maru / sp. nov. / Seidel et al. 2019”. Pൺඋൺඍඒඉൾඌ: NEW ZEALAND: SඈඎඍΗ Iඌඅൺඇൽ: Mid Canterbury: 4 JJ 13 ♀♀

( NZAC, NMPC, BMNH, ZMH): Rangitata River at Rangitata Gorge Road, Ashburton Lakes, 415 m, 16.xii.2018, huge exposed river and its side arms in enormous riverbed, R.Leschen & V.Sýkora lgt. 2018- NZ 97.

Description of adults [characters identical to B. pallidipennis description are not repeated]. Body length 3.5–4.5 mm (holotype: body length: 4.4 mm; humeral width: 1.7 mm). Shape elongate ellipsoid ( Figs 2B, F ).

Coloration. Maxillary palpi with palpomere 4 darkened in apical third.

Dorsum. Pronotal surface without long pale decumbent setae. Surface of elytra smooth in males, with mesh-like microsculpture in females. Elytral apices slightly to nondivergent in males, slightly divergent and rounded in females leaving a narrow 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 shallow and narrow notch in males, and a wide, deeply rounded notch in females.

Legs. Male protarsus with adhesive soles on tarsomere 1, which is ca. twice as thick as following tarsomeres; tarsomere 4 as long as tarsomeres 1–3 combined.

Male genitalia. Total length 1.5 mm. Parameres long, narrow, gradually acuminate, apical half sinuate and not 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.

Differential diagnosis. Berosus maru sp. nov. differs from B. muellerorum sp. nov. and B. halasi sp. nov. by its smaller body size and large rectangular spot on the pronotum; in both these characters as well as in most other external characters it is very similar to B. pallidipennis with which it may co-occur. For diagnosis from B. pallidipennis , see under that species.

Etymology. The species is named after Maru, the Maori god of fresh water also known as the god of war in Southern New Zealand. The name is a noun in the nominative case, standing in apposition.

Habitat. This species was collected in semi-permanent pools along rivers ( Fig. 3F ).

Distribution ( Fig. 3B ). Central part of the South Island (Mid Canterbury, North Canterbury).

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.