Metopiellus palamaku, Tapuy-Avilés & Díaz-Guevara & Caterino, 2026

Tapuy-Avilés, Yarina, Díaz-Guevara, David R. & Caterino, Michael S., 2026, First country record of Metopiellus Raffray, 1908 (Staphylinidae, Pselaphinae, Metopiasini) from Ecuador, with description of two new species, ZooKeys 1266, pp. 127-135 : 127-135

Metopiellus palamaku sp. nov.

Figs 1 A – C , 2 A – C

Type material.

Holotype ♂ ( MECN -EN 23780 ): “ Ecuador. Napo: Chontapunta, R. Minga , -0.88692, -77.27049, 300 m. Winkler. 07-feb-2023, Díaz-Guevara & N. Berrazueta ” / “ MECN -EN 23780 ”; deposited in MECN .

Additional, non-type material.

Ecuador • 1 ♀; Orellana; 0.6376°S, 76.1499°W; Tiputini Biodiv. Sta. ; 2-9.vi.2011; general hand collecting, AT 1341, M. Caterino, A. Tishechkin; Caterino DNA voucher, Ext. MSC-12663 ; ZSFQ-i 16787 • 1 ♀; Panayacu, Yasuní , 0°42'17.6"S, 76°40'15.7"W; 340 m; Winkler; 17 Jul. 2021; Pazmiño-Palomino; MECN -EN 48730 .

Comparative diagnosis.

Metopiellus palamaku sp. nov. strongly resembles M. guanano , having a vertex with a single horn-like projection. However, M. palamaku can be easily differentiated by its single pair of mediolateral, thick, spinose pronotal projections (vs. two pairs in M. guanano ), the presence of basal elytral foveae (absent from M. guanano ), and by aedeagal characters including a more elongate basal bulb, and differently shaped articulated armature (Fig. 2 ), bifid at the tip with subapical hook bent at ~ 90 ° (vs. aedeagal armature simply tapered, slightly sinuate at apex in M. guanano ; aedeagal armature with four spatulate, curved tips in M. emavieirae ).

Description.

Avg. BL = 2.7 mm ( N = 2; see Table 1 for other measurements). Body (Fig. 1 A – C ) densely setose and brown; eyes prominent, comprising ~ 11 ommatidia; head pyriform with two vertexal foveae near posterior margin with a single median process similar to M. guanano ; antennae with 11 antennomeres, antennal scape base thick and slightly narrowed before the apex (in dorsal view), antennomere I as long as rest of the antennomeres combined, antennomere II about as long as III – VIII combined, III-IV and VI slightly longer than wide, V distinctly longer, VII globular, VIII small, IX and X slightly transverse, XI almost as long as IX – X combined, tapered in apical half; pronotum trapezoidal, wider anteriorly and narrower posteriorly, with two pairs of mediolateral, thick, spinose projections; each elytron with two basal foveae, and with longitudinal impressions extending from them posteriorly approximately two-thirds elytron length. Aedeagus (Fig. 2 A – C ) with large, elongate basal bulb, slightly asymmetrical, with smoothly rounded basal margin; dorsal diaphragm large, elongate oval; tegmen narrowed toward flat, paddle-shaped apex; elongate armature articulated within basal bulb, apex bifid, with acute, subapical hook bent at ~ 90 °, other tip slightly diverging to left, acute.

Distribution.

This species is known from the type locality in Chontapunta, Ecuador (Fig. 3 ), and probably also from the Tiputini region of Orellana (if the associations of the females under ‘ other material’ are correct). The sites are separated by about 125 km, but are all on the same (south) side of the Rio Napo.

Etymology.

The specific name derives from a Kichwa legend in which Palamaku is the divine source of insects.

Figures

Figure 1. Habitus of new Metopiellus species. A – C. M. palamaku sp. nov. (female dorsal, female lateral, male holotype ventral); D – F. M. chasqui sp. nov. (male holotype dorsal, female paratype head + pronotum, male non-type head only). Scale bars: 1 mm (unless otherwise indicated).

Figure 2. Aedeagus of new Metopiellus species (dorsal, lateral, ventral). A – C. M. palamaku sp. nov.; D – F. M. chasqui sp. nov.

Figure 3. Map of Ecuador showing type localities of the two new species.