Pycnomerus taralewisae, Porch & Smith & Greig, 2020

Porch, Nick, Smith, Tessa R. & Greig, Kelly, 2020, Five new Pycnomerus Erichson (Coleoptera: Zopheridae: Pycnomerini) from Raivavae, French Polynesia, Zootaxa 4718 (2), pp. 239-250 : 245

Pycnomerus taralewisae sp. nov. Porch & Greig

( Fig.1 , 4 )

Type Locality: Raʹirua Swamp, 0.8 km E. of Raʹirua, at 23°52.115’S 147°40.718’W.

Type material. Holotype: French Polynesia, Austral archipelago, Raivavae, Raʹirua swamp, DA4 cores, 245– 250 cm depth—prothorax, dorsally and ventrally complete except for appendages. BPBM, Honolulu.

Paratype: French Polynesia, Austral archipelago, Raivavae, Raʹirua swamp, DA4 cores, 225–230 cm depthprothorax, dorsally and ventrally complete except for appendages (disk cracked from base) . BPBM, Honolulu.

Diagnosis. Distinguished from co-occurring species and those from Rimatara ( Porch & Smith 2017) and Tubuai (Greig & Porch, unpubl. data) by its combination of arcuate lateral margins, base wider than apex, and large, shallow-edged, punctures that become confluent laterally, especially in apical half.

Description. Based on holotype and one paratype.

Colour: Dark piceous-black.

Prothorax approximately as long as wide with greatest width just in front of 1/2 of pronotal length. Lateral margins moderately arcuate, straighter to near basal angles, unevenly and coarsely crenulate, with crenulae stronger behind middle. Margin narrower than lateral sulcus, widened to basal angles. Marginal sulcus narrowed to anterior angles and continuous with basal sulcus around basal angles. Anterior angles obtuse and very weakly produced. Anterior margin slightly emarginate medially, sinuate to anterior angles and unbordered. Posterior angles obtuse but distinct. Posterior margin arcuate and posterior border sparsely punctate. Basal sulcus wider than basal border, anteriorly interrupted by discal punctures except over middle quarter. Pronotal disk strongly punctate with deep but shallow-edged punctures coalescing into longitudinal rows in front of middle, creating weakly raised ridges between puncture rows. Punctures less dense, separated by half to more than one puncture width medially and behind middle, but closer laterally where some punctures coalesce creating narrower but more elevated ridges between. Surface of disk moderately shining between punctures. Small pale yellow setae, shorter than the punctures remain in several punctures.

Prosternum densely punctate with deep circular punctures separated by half their own width or less, closer on prosternal process and especially its apex where they coalesce. Microsculpture slightly stronger than pronotal disk. Light yellow setae protruding from posterior edge of some punctures oriented anteriorly. Anterior edge thinly bordered and sparsely punctate. Apex of prosternal process angularly emarginate. Hypomera punctate.

Physical dimensions and Ratios.

Pronotum measurements based on holotype and paratype. Measurements of holotype in parentheses. Pronotum length: 0.69–(0.90) mm. Pronotum width: 0.67–(0.89) mm. Anterior width of pronotum: 0.51–(0.69) mm. Medial width of pronotum: 0.66–(0.88) mm. Base of pronotum: 0.59–(0.73) mm. Lateral length of pronotum 0.62–(0.80) mm. Length/Width ratio: (1.01)–1.03.

Prosternum measurements based on holotype and paratype. Prosternum length: 0.42–(0.55) mm. Length prosternum in front of coxae: 0.26–(0.34) mm. Anterior foramen: 0.48–(0.64) mm. Basal foramen: 0.46–(0.57) mm. Prosternal process intercoxal width: 0.21–(0.26) mm. Maximum prosternal process width: 0.27–(0.36) mm. Ratio of Prosternal length/Length in front of coxae: 1.62–(1.62).

Distribution. Known only from Raʹirua swamp, Raivavae, and likely to be a Raivavae endemic. Potentially ex- tinct: material known from other Austral Archipelago islands (Tubuai, Raivavae and Rapa) and nearby Cook Islands (Mangaia and Atiu) represent different taxa.

Etymology. Named for friend and colleague Tara Lewis who has worked extensively on sorting and identification of Holocene flora and fauna from the Indo-Pacific region including helping Porch collect and process subfossil material on Raivavae in 2016.

Figures

FIGURE 1. Holotypes. Pycnomerus raivavae articulated prothorax and head, dorsal (top) and ventral (bottom)—(French Polynesia, Austral archipelago, Raivavae, Raʹirua swamp, RAI16-2 2016 cores, 150–200 cm depth). Pycnomerus rairua prothorax, dorsal (top) and ventral (bottom)—(French Polynesia, Austral archipelago, Raivavae, Raʹirua swamp, DA4 cores, 180–185 cm depth). Pycnomerus vavitu prothorax, dorsal (top) and ventral (bottom)—(French Polynesia, Austral archipelago, Raivavae, Raʹirua Swamp, DA4 2008 core, 170–175 cm depth). Pycnomerus mahanatoa prothorax, dorsal (top) and ventral (bottom)—(French Polynesia, Austral archipelago, Raivavae, Raʹirua Swamp, DA4 2008 core, 205–210 cm depth). Pycnomerus taralewisae prothorax, dorsal (top) and ventral (bottom)—(French Polynesia, Austral archipelago, Raivavae, Raʹirua swamp, DA4 cores, 245–250 cm depth). Scale bars = 0.5 mm

FIGURE 4. Dorsal and ventral views of prothoraces of P. vavitu and P. taralewisae. Holotypes indicated (with ‘HT’). Scale bar = 0.5 mm.