Prionohydrus cambyreta Urcola, Baca, Rodriguez & Michat, 2024, sp. nov.
Creators: name: Urcola, Juan I.
name: Baca, Stephen M.
name: Rodriguez, Georgina
name: Michat, Mariano C.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Noteridae
Prionohydrus
Prionohydrus cambyreta

description: Prionohydrus cambyreta sp. nov.
(Figs 1–7)
Type locality. Argentina, Corrientes Province, Parque Nacional Iberá, Portal Cambyretá, 27°49’S 56°50’W, elevation 75 m a.s.l.; specimens collected by light trapping.
Type material. Holotype ♂ labelled: “ ARGENTINA. Corrientes / Province. PN Iberá. Portal / Cambyretá 16.XI.2018 / Col.: Urcola JI ” [typed, white label], “HOLOTYPE / Prionohydryus cambyreta sp. nov. / Urcola et al. 2024 ” [typed, red label], “ MACN _En / 43449” [typed, white label]. Paratypes: same data as holotype, 15 ♂, 15 ♀ (MACN-EN 43450 to 43479). All paratypes with the following label: “PARATYPE / Prionohydryus cambyreta sp. nov. / Urcola et al. 2024 ” [typed, yellow label].
Diagnosis. Prionohydrus cambyreta sp. nov. is distinguished from other species of the genus by the following combination of characters: (1) ventral coloration red-brown (2) male antennae strongly expanded, (3) lateral flanges on sides of median lobe unequal, left lateral flange strongly expanded ventrally, (4) left lateral lobe with a tuft of very long hair-like setae on proximal third, followed by a second tuft of shorter hair-like setae, (5) lateral projection of left lateral lobe rounded, and (6) apex of left lateral lobe with a tuft of hair-like setae of different lengths.
Description of the holotype. Small sized beetle (TL = 2.1 mm). Body elongate, subovate, broadest at about basal third of elytra, posteriorly strongly attenuated apically (Figs 1a–b); in lateral view dorsum convex, lateral outline slightly discontinuous between pronotum and elytron (Fig. 1c).
Color (Figs 1a–c). Head and pronotum reddish-brown; elytron slightly darker. Ventral coloration reddish-brown except abdominal ventrites and legs lighter; antennae and palpi orange brown.
Dorsal surface (Fig. 1a). Head, pronotum, and elytron densely covered with moderately impressed isodiametric meshes (Figs 1a, c, 6b–d). Head broad, with very fine irregular micropunctation near internal margin of eyes; eyes medium-sized (Fig. 1a, HW/EW = 1.7). Pronotum convex, bead narrow posteriorly, evenly expanded anteriorly to broad anterior angle; surface with transverse row of micropunctation near anterior margin; anterior and lateral margins with golden setae. Elytra convex; maximum width at about anterior third; each elytron with five longitudinal rows of macropunctation, with long golden setae near lateral margin and on posterior region.
Ventral surface (Fig. 1b). Head, thorax, legs, and abdomen dull, densely covered with moderately impressed isodiametric meshes (Figs 1b, 3), except for somewhat more transverse meshes anteromedially on prosternum (Fig. 3a) and somewhat more longitudinal meshes on lateral margin of prosternal process (Fig. 3b). Antennae strongly expanded (Figs 1a–b, 2a, 3a, 4a–b); antennomeres I and II subequal in length; antennomeres III–V short, not strongly widened; antennomere VI–XI long, strongly widened, with microtrichia (groups of minute cuticular protuberances which lack socket) on ventral surface, denser on antennomeres X–XI (Fig. 4a–b, e–f); antennomere XI longest; antennomere VII widest. Maxillary palpus with palpomeres I–III short; palpomere IV slightly shorter than first three combined, notched at apex. Labial palpus with palpomeres I–II very short, subconical; palpomere III as long as first two combined, broad and flat with small protuberance on inner margin. Prothorax with prosternum longitudinally relatively elongate, medially broadly convex (Figs 1b, 3a); apparently glabrous (under low magnifications, Fig. 1b) but with some minute, either hair-like or spine-like setae (Fig. 3a); prosternal process (Fig. 1b, 3a–b) narrow between procoxae, then widening to subrectangular plate with lateral margins almost straight, posteriorly strongly attenuated with apex slightly rounded (Figs. 1b, 3b). Metacoxal processes (Fig. 3a) subtriangular, with some short, stout setae scattered over entire surface, more abundant posteromedially; lateral margins slightly divergent posteriorly, metacoxal lobes evenly rounded with a cluster of setae apically (Fig. 3d), posterior margin sinuate (Fig. 1b, 3a). Anterior leg (Figs 2c, 3a) with profemur short and broad, protibia short and rounded dorsoapically, with moderately large, weakly curved, apical spur and moderately large dorsal spur, with shortened fringe of setae along apical margin, with hair-like setae on dorsal margin and anterodistal surface; protarsus attached to apex of protibia, protarsomere I largest, as long as protarsomeres II–V combined, bearing a single suction cup (Fig. 3c), protarsomeres II–IV subequal in length, protarsomere V slender, as long as protarsomeres II–IV combined. Medial leg (Fig. 3a) with mesofemur and mesotibia long and slender; mesotibia with several moderately large spines, posterior spur strongly serrate (Fig. 6a), mesotarsomere I as long as mesotarsomeres II–IV combined, with a single suction cup (Fig. 3e). Posterior leg (Figs 2d, 3a) with metafemur broader (FW/FL = 0.46), with thick comb of long setae on posterodistal angle; metatibia long and somewhat broad, with several moderately large spines (smaller in size than mesotibial spines), a series of long natatory setae on inner margin, and two spurs on distal inner angle, posterior spur longest and strongly serrate, anterior spur not serrate (Figs 2d, 3a, 6a). Claws subequal in length, without teeth. Abdomen subtriangular, composed of six ventrites; ventrites I–III fused; suture separating ventrite 1 from ventrite II well visible, suture separating ventrites II and III indistinct; ventrite VI subtriangular, with long golden setae at apex.
Male genitalia (Fig. 5). Sternite IX ring-like, posterior margin bilobed with deep notch, ventrite IX with an oval sclerotized area, apically protruding, apex pointed with several minute hair-like setae (Fig. 5a); aedeagus asymmetrical; median lobe (Fig. 5b–d) slender, in lateral view sinuate, then narrowing to rounded apex; curved dorsally at about mid-length; ventrally with deep longitudinal groove subtended by lateral flanges, left lateral flange (Fig. 5b) enlarged, strongly expanded ventrally, converging with right lateral flange at or near apex; base comprised of right lateral notch and a medial hook-like process (left lateral notch reduced); right lateral lobe in lateral view (Fig. 5e) short, subtriangular, laminar, narrow at base, broadening towards apex, with deep longitudinal groove on dorsal side, creating an inward fold; left lateral lobe large, heavily setose, in lateral view (Fig. 5f–g) relatively elongate, broad, curved, with a tuft of very long hair-like setae on proximal third, followed by a second tuft of shorter hair-like setae, and an elongate and rounded projection on left side (Fig. 5g); apex broad, rounded, with a tuft of hair-like setae of different lengths.
Measurements. Holotype [paratypes, mean]: TL = 2.1 mm [2.1–2.3 mm, mean = 2.19 mm]; GW = 1.1 mm [1.10–1.2 mm, mean = 1.15 mm]; PL = 0.5 mm [0.5–0.55 mm, mean = 0.51 mm]; PW = 1.0 mm [1.05–1.15 mm, mean = 1.08 mm]; HW = 0.7 mm [0.7–0.8 mm, mean = 0.75 mm]; FL = 0.4 mm [0.35–0.45 mm, mean = 0.40 mm]; FW = 0.2 mm [0.15–0.2 mm, mean = 0.18 mm]; SW = 0.1 mm [0.1–0.15 mm, mean = 0.14 mm]; TLVP = 0.9 mm [0.9–1.05 mm, mean = 0.99 mm]; TL/GW = 1.9 [1.80–2.0, mean = 1.91]; PL/PW = 0.5 [0.45–0.50, mean = 0.47]; HW/EW = 1.7 [1.67–1.88, mean = 1.73]; FW/FL = 0.5 [0.45–0.5, mean = 0.46]; GW/SW = 8.4 [7.85–9.6, mean = 8.73].
Female genitalia (Fig. 7). No conspicuous differences were observed with the female genitalia of P. matogrossensis.
Sexual dimorphism. Male antennae strongly expanded (Figs 2a, 3a, 4a–b); females with antennae unmodified (Figs 2b, 4c–d, 6a). Apex of prosternal process more rounded in females (Fig. 6e) than in males (Fig. 3b). Male proand mesotarsomeres I as large or larger than segments II–IV combined, bearing a single suction cup (Figs 2c, 3a, c, e); females with pro- and mesotarsomeres I large but smaller than segments II–IV combined, lacking suction cups.
Differential diagnosis. Prionohydrus species exhibit a high degree of morphological similarity and few reliable external characteristics are available for distinguishing between them. Only subtle differences in ventral coloration and in antennal shape of males and females serve as diagnostic characters (Gómez & Miller, 2013). Therefore, a thorough examination of the genitalia is imperative for accurate species identification. In appearance, the new species closely resembles P. matogrossensis as it exhibits a ventral red-brown coloration and an evident sexual dimorphism in antennal shape, with the antennae of males strongly expanded and those of females unmodified. In contrast, P. marc has a ventral light yellow-brown coloration, and the antennae of males are only slightly expanded (unmodified in females). Prionohydrus ubercornis, on its part, exhibits the same ventral light yellow-brown coloration as P. marc, but in this case both males and females have strongly expanded antennae. Prionohydrus cambyreta sp. nov. can be differentiated from P. matogrossensis by the median lobe of male genitalia: the lateral flanges of median lobe are unequal in height in the new species (Fig. 5b, d), whereas in P. matogrossensis they are subequal in height (Figs 9–10, in Gómez & Miller, 2013). Prionohydrus cambyreta sp. nov. has similar median and right lateral lobes as P. marc and P. ubercornis, but the left lateral lobe exhibits some differences. Prionohydrus ubercornis has a single tuft of hair-like setae on basal two thirds (Fig. 16, in Gómez & Miller, 2013), whereas the other two species present two tufts, one on proximal third composed of long setae, and a second tuft distal to the first one composed of shorter setae (Fig. 5f–g). Finally, the left lateral lobe in P. cambyreta sp. nov. has an elongated and rounded projection on the left side (Fig. 5g), and the apex bears a tuft of long hair-like setae of different lengths (Fig. 5f–g), whereas in P. marc the projection is elongated and narrowed, and the tuft of hair-like setae on apex is composed of setae of similar length (Fig. 13, in Gómez & Miller 2013).
Distribution. Northeastern part of Argentina (Corrientes Province) (Fig. 8).
Etymology. The specific epithet “cambyreta ” is a noun in apposition that refers to the site where the new species was found.
description: Published as part of Urcola, Juan I., Baca, Stephen M., Rodriguez, Georgina & Michat, Mariano C., 2024, Prionohydrus cambyreta sp. nov. from Iberá wetlands-the first species of the genus from northern Argentina (Coleoptera: Noteridae), pp. 483-493 in Zootaxa 5523 (4) on pages 484-491, DOI: 10.11646/zootaxa.5523.4.7, http://zenodo.org/record/13949745