Limbodessus moni, Surbakti & Balke & Hendrich, 2023

Surbakti, Suriani, Balke, Michael & Hendrich, Lars, 2023, Limbodessus moni sp. nov., a new high altitudinal diving beetle from the Grasberg in West Papua, Indonesia (Coleoptera: Dytiscidae, Bidessini), Zootaxa 5319 (3), pp. 413-420 : 414-419

Limbodessus moni sp. nov.

Type locality. Grasberg (-4.0622° 137.1429°), 3,970 m, West Papua, Indonesia. Type material: Holotype: Male, “ Indonesia:Papua, Grasberg, 3,970 m, viii.2018, (-4.0622° 137.1429°, Surbakti”, “HOLOTYPE / Limbodessus moni sp.n. / Surbakti, Balke & Hendrich det. 2023” [red printed label] ( MZB).

Paratypes: Three males and one female with same data as holotype ( MZB, KSP, ZSM). 9 males and 2 females: “ Indonesia, Irian Jaya, Lake Anderson [3,555 m] nr Grasberg, 23.iii.1997, D. Polhemus ” ( USNM, ZSM). Each paratype is provided with a red printed paratype label .

Additional material studied: 2 males and 2 females: “ Indonesia, Irian Jaya, Dom nr Grasberg mine, around 4000 m, 20.iii.1997, J. Polhemus ” ( USNM). These four specimens are not included in the paratypes because they are smaller and the shape of the body is more broadly oval. Furthermore, the two females are shiny without fine microreticulation on dorsal surface. Further studies involving additional material and molecular data will determine whether these specimens belong to L. moni sp. nov. or to another undescribed species .

Description of the holotype

A large, brownish black Limbodessus , with distinct habitus disruption between pronotum and elytron.

Coloration: Head dark reddish brown, antennomeres testaceous, with antennomeres 4 to 11 blackish anteriorly. Pronotum testaceous, basal half–except basal corner–darkened, anterior margin of pronotum black. Elytron completely dark blackish-brown ( Fig. 1A ). Ventral side, including metacoxal plates dark reddish brown; prosternal process and epipleura testaceous; fore legs dark brownish with testaceous knees, mid legs almost black, hind legs blackish, with tibiae and tarsomeres basally testaceous.

Sculpture and structure: Head: Punctation fine, somewhat sparse, posteriorly slightly coarser and somewhat denser. Microreticulation visible but very fine, shiny. Cervical line not present.Antenna filiform. Pronotum: Broadest at middle. Punctation coarse, dense, almost evenly distributed, microreticulation absent. Sides of pronotum margined and almost evenly rounded. Angle between pronotum and elytra rather distinct; pronotal plicae present, slightly curved, 2/3 length of pronotum and strongly impressed. Elytra: Elytral plicae short, slightly curved inwards, 1/10 length of elytra. Punctation coarse, dense, almost evenly distributed, microreticulation absent, shiny ( Fig. 1 ). Ventral side: Base of elytral epipleuron simple, without raised transverse carina delineating a basal pit. Metacoxae and metaventrite with few punctures, surface shiny, without microreticulation. Elytral epipleuron apically modified: slightly concave, with inner margin dilated.

Median lobe ( Fig. 2 ) of aedeagus in ventral (A) and lateral (B) view. Left paramere, view on inner side (C) and right paramere, view on outer side (D).

Females: Antennomeres 4–11 slightly enlarged ( Fig. 1B ). Dorsal surface with very fine microreticulation between punctures and therefore appearing matt ( Figs 1B , 4 ).

Variability: Some specimens with more brownish elytron as in Fig. 1B .

Measurements. Holotype: TL = 2.7 mm, TL-H = 2.35 mm, MW = 1.15 mm, TL/MW = 2.35. Paratypes, males: TL = 2.3–2.7 mm, TL-H = 1.9–2.25 mm, MW = 0.95–1.0 mm, TL/MW = 2.16; females: TL = 2.25–2.55 mm, TL-H = 1.75–1.9 mm, MW = 1.0– 1.1 mm, TL/MW = 2.

Etymology. The species is named after the Moni, an indigenous people mainly settling in the mountain areas of New Guinea around the type locality. The name is a noun in the nominative singular standing in apposition.

Differential diagnosis. The new species can be easily separated from most of the other New Guinean Limbodessus by its almost completely blackish surface ( Fig. 1 ). Limbodessus moni sp. nov. is close to the only other blackish species L. alexanderi Balke & Hendrich, 2015 , but can be separated by the shape of the median lobe (compare Figs 2A, B and 3A, B ), the shape of the parameres (compare Figs 2C, D and 3C, D ), the presence of elytral plicae ( Figs 1A, B ) (absent in L. alexanderi , Figs 1C, D ), and the only slightly enlarged female antennomeres 4–11 ( Fig. 1B ), not forming a conspicuous club as in L. alexanderi ( Fig. 1D ) ( Balke et al. 2015, Hendrich et al. 2020).

Distribution. Known only from two localities around the Grasberg Mine and Anderson Lake (Carstenz Pyramid area), between 3,550 and 3,970 m, in West Papua, Indonesia ( Fig. 5 ).

Ecology. Small puddles with mossy edges in high altitude grassland in a tropical subalpine habitat ( Fig. 6 ). All beetles were collected with a small kitchen strainer, and no other diving beetle species than L. moni sp. nov. were recorded in these habitats.

Conservation. Most likely the species is not threatened by human impacts due to its occurrence on remote high-altitude plateaus.

Figures

FIGURE 1. A) Limbodessus moni sp. nov., holotype, male; B) L. moni sp. nov., female; C) L. alexanderi, male; D) L. alexanderi, female (Scale bars = 1 mm).

FIGURE 2. Limbodessus moni sp. nov., median lobe of aedeagus in ventral (A) and lateral view (B); left paramere, view on inner side (C) and right paramere, view on outer side (D). Scale bar = 0.2 mm.

FIGURE 3. Limbodessus alexanderi, median lobe of aedeagus in ventral (A) and lateral view (B); left paramere, view on inner side (C) and right paramere, view on outer side (D). Scale bar = 0.2 mm.

FIGURE 4. Head of L. moni sp. nov. Scale bar = 0.2 mm.

FIGURE 5. Distribution of Limbodessus species in New Guinea and adjacent islands. The widespread Limbodessus compactus can be found everywhere in New Guinea, at altitudes between sea level up to 1,900 m.

FIGURE 6. Habitat of Limbodessus moni sp. nov. around the Grasberg (Carstenz Pyramid area) at 3,970 m. The first author in front of the Grasberg Mine (A) and the habitat where part of the type material was collected (B).