Diastoleus alveolaris Pinto & Zúñiga-Reinoso, 2025

Diastoleus alveolaris Pinto & Zúñiga-Reinoso sp. nov. ( Figs. 1c View FIGURE 1 , 2 View FIGURE 2 and 3 View FIGURE 3 )

Type material. Holotype (♂), Chile, Atacama region, Chañaral, Parque Nacional Pan de Azúcar, Quebrada de los Sapos (-26.166, -70.623). 400 m asl. 08.II.2022. Leg P. Pinto ( MNNC) GoogleMaps . Allotype (♀), with the same date and locality than holotype [ MNNC] . Paratypes: 7 specimens with the same date and locality than holotype: 1♂ / 2♀♀ [ PPPC] , 2♀♀ [ MZUC] . 1♀ [ IADIZA] , 1♀ [ SLPC]), and 2 specimens obtained by breeding (1♂ / 1♀ [ PPPC]) . 2 specimens from Chile, Atacama region, Chañaral, Parque Nacional Pan de Azúcar, Route C110, 6.5 km E of the Caleta Pan de Azúcar (-26.125°, -70.598°). 180 m asl. 15.X.2017. Leg A. Zúñiga : 2♀ [ MZUC: voucher DiasA20_1 and DiasA20_2] . 1 specimen from Chile, Atacama region, Chañaral , 6 km E Caleta Pan de Azúcar, 11-III-2017, 26.12451°S, 70.60144°W, 152m, Leg. L. Ragionieri, A. Zúñiga, M. Bleiser, G. Flores, R. Predel ( IADIZA) GoogleMaps .

Description. Body elongate, brown and shiny, strongly constricted between pronotum and elytra ( Figs 2a and b View FIGURE 2 ). Head opaque brown, sub-square and glabrous ( Fig. 2c View FIGURE 2 ). Labrum sub-square covered with thick and dense pilosity directed forward. Clypeus slightly raised, with conspicuous notch in central area of anterior margin and abundant, marked and irregular punctuation ( Fig. 2c View FIGURE 2 ), lateral margins of clypeus marked and raised. Frons with sparse, coarse, irregular and deep punctures, vertex slightly raised with deep and thick punctures. Lateral margins of head (i.e. from clypeus to epicanthus) thick and folded almost 90° upwards. Antennae slightly capitate, extending towards posterior third of pronotum. Antenomeres I–VII with irregular and deep punctuation, short setae on anterior margin, antenomeres III 3x longer than others, antenomeres VIII–XI wider than long, smooth with clusters of placoid sensilla, antenomeres XI acute. Pronotum (excluding expansions) dark brown and shiny, 1.5x wider than long, widest at middle, punctures sparse and weak on the anterior margin of the pronotum and more abundant and deeper towards base. Pronotal disc raised and smooth, three slight dents on base of pronotum, one central and two towards lateral margins ( Fig. 2a View FIGURE 2 ). Pronotal expansions light brown and shiny, with slight wrinkles directed towards margins, being at base more marked than towards apex, notch of pronotal expansion U-shaped, opening very slightly towards apex and base of notch slightly angled ( Fig. 2a View FIGURE 2 ). Punctures sparse over the entire dorsal surface of the expansions, but more abundant and conspicuous at the base, against backlight there is a visible reticulate pattern forming rounded cells, with appearance of enclosed bubbles ( Fig. 2d View FIGURE 2 ). Hypomeron without punctures. Prosternum smooth, slightly punctured, anterior margin slightly raised, with row of short setae directed forward. Apex of prosternal process inclined downwards, slightly punctured and wrinkled ( Fig. 2b View FIGURE 2 ). Anterior margin of the mesoventrite, thick and rough, with thin and short pilosity on first half and posterior half slightly wrinkled and punctured. Metaventrite semi-bright, smoothly wrinkled, punctures sparse and not deep. Elytra brown, oval and acuminate towards apex, 1.45x longer than wide, elytral suture slightly raised. Each elytron with five dorsal carinae and intercostal punctures marked in longitudinal rows ( Fig. 2a View FIGURE 2 ). Carina I (i.e. closest to elytral suture) discontinuous, visible on the anterior third and reappearing as small spiny tubercles near elytral apex. Carina II slightly elevated and entire, forming fused spiny tubercles towards apex ( Fig. 2e View FIGURE 2 ). Carina III slightly raised, with interrupted sections and ending in separated spiny tubercles towards apex ( Fig. 2e View FIGURE 2 ). Carina IV well raised and marked, entire, slightly sinuate and ending with a spiny edge towards the apex. Carina V raised but discontinuous in the last third of the elytra, ending in separated spiny tubercles on elytral declivity but not reaching apex ( Fig. 2e View FIGURE 2 ). Elytral margin formed by a raised carina ( Carina VI ), markedly serrate towards apex. Pseudopleuron with a single carina slightly raised and discontinuous (carina VII), only present in first half. With a row of longitudinal punctures located between carinae VII and VI and three rows of longitudinal punctures below carina VII. Epipleuron with raised margin and smooth. Ventrites I and II same size and longer than ventrites III and IV ( Fig. 2b View FIGURE 2 ), semi-smooth and shiny, with slight longitudinal wrinkles towards apex. Ventrites III and IV with irregular punctures and dented on lateral margins. Ventrite IV shorter than rest and ventrite V opaque strongly punctured. Legs opaque and brown, femora and throcanter thick and fully punctured near to coxa. Tibiae with spines-like tubercles over whole surface ( Fig. 2b View FIGURE 2 ), apical tarsomere larger than other tarsomeres.

Male genitalia. Aedeagus glabrous, lateral styles (ls) narrowing abruptly towards apex giving triangular appearance, base of ls curved and not bisinuate. Basal lamina with sub-parallel lateral margins, 1.54x longer than ls, narrowing in last third towards its base and rounded base ( Fig. 2f View FIGURE 2 ).

Female genitalia. Ovipositor subtriangular, short and glabrous (except by gonostyli). With two barely visible coxites. Coxites widest on base sharpening towards apex. Coxite 4 with sensory setae on base. Paraproct subequal in length to coxites, with lateral margin almost straight ( Fig. 2g View FIGURE 2 ).

Mature Larva. Body elongate-cylindrical, yellowish, highly sclerotized with body length of 32 mm ( Fig 3a View FIGURE 3 ). Head darker, slightly narrower than prothorax, declined; globular but slightly flattened dorsoventrally, slightly wrinkled ( Fig 3b and c View FIGURE 3 ). Epicranial suture Y-shaped but barely visible ( Fig 3c View FIGURE 3 ), lateral margins of head with a row of erect setae ( Fig. 3d View FIGURE 3 ). Labrum transverse, anterior margin bisinuate with a row of abundant setae directed forward, disc of labrum with a single line of 9–10 setae ( Fig. 3b View FIGURE 3 ) and lateral margin with strong setae. Clypeus wrinkled with a transverse dent on middle with a row of small dark setae ( Fig. 3b View FIGURE 3 ), frons wrinkled and glabrous except for two small dark setae on anterior margin. Ocelli not evident ( Fig. 3b and d View FIGURE 3 ). Maxillary palpi three-segmented, cylindrical, and conical at apex; I widest, II longest. Labial palps two-segmented, II conical, mentum subsquare, anterior margin with a central directed forward projection of same size as first segment of labial palp ( Fig. 3e View FIGURE 3 ) and four long setae directed forward close to anterior margin. Base of mentum straight, submentum with long setae. Antennae three-segmented and cylindrical at apex: I widest, II longest; III shortest and narrowest barely visible as a rudiment ( Figs 3b and c View FIGURE 3 ). Thoracic segment parallel-sided, widest on the base, with transverse plicae. Pronotum darker, wrinkled and with a Y-shape dent on disc ( Fig. 3c View FIGURE 3 ), longest, 1.6 x times as long as mesonotum, 1.2x as long as metanotum, mesonotum shortest. Thoracic spiracles covered by a fold, prothoracic spiracle constrained as a small dark line, meso-metathoracic spiracle oval and mesothoracic spiracle almost twice as long as abdominal segment I spiracle ( Fig. 3e View FIGURE 3 ). Prothoracic legs remarkably bigger than meso- metathoracic legs ( Figs 3b and e View FIGURE 3 ), tarsungulus strongly sclerotized, sharp as a single claw-like ( Fig. 3e View FIGURE 3 ). Tibiae with spine-like setae on ventral face, more abundant in protibiae. Profemora with 8–9 spine-like setae, meso-metafemora with 5 spine-like setae on ventral face ( Fig. 3e View FIGURE 3 ), profemora subtringular and thicker, meso-meta femora subcylindrical and thinner. All trochanters oval but protrochanter thicker with two spine-like setae on apex of ventral face, meso-meta trochanters with a ring of setae on apex, two of them spine-like on ventral face. Coxae subcylindrical with long setae on dorsal and ventral face ( Fig. 3d View FIGURE 3 ). Abdomen, approximately 4.3x as long as thorax, abdominal segments I–VIII subcylindrical, with transverse darker plicae ( Fig. 3a View FIGURE 3 ), dorsally with two foveae on first half of each segment ( Fig. 3f View FIGURE 3 ), these foveae form a slightly raised transverse ridge on each segment ( Fig. 3a View FIGURE 3 : dorsal and lateral view). Ventrally, with foveae from segments II to VIII ( Fig. 3a View FIGURE 3 ), foveae of segments II, VII and VIII circulars, two above and two below, segments III -VI with two circulars foveae nearer anterior margin of each segment and one transverse fovea below these. Last segment IX acuminate, 0.7 times shorter than abdominal segment VIII and distinctly narrower than VIII, the disc surface convex with few short setae in ventral view ( Fig. 3g View FIGURE 3 ). Urogomphi turned upwards with apex acuminate ( Fig. 3h View FIGURE 3 ), on each side of apex a row of 9–10 dark, short, spine-like setae running along dorsal edge ( Fig. 3f and h View FIGURE 3 ). Lateral margin of abdominal segments I–VIII each with pair of round spiraculae of similar size and not covered ( Fig. 3a View FIGURE 3 : lateral view).

Diagnosis and comments. D. alveolaris sp. nov. is morphologically very close to D. costalenis but the diagnostic character listed below allow to distinguish between the two species. Body elongate, brown and shiny. Lateral margin of the head, thick and folded almost 90°. Pronotal expansions with rounded reticulate pattern. Elytral carinae ending in rows of spiny tubercles near elytral apex. Edeagus with lateral styles (ls) narrowing abruptly from base, base of ls not bisinuate.

Intraspecific variability. The size of the specimens is highly variable. The average body length of the specimens studied was 17.74 mm with a range between 16.22 mm and 19.56 mm. The shape of the pronotal expansion notch is variable, sometimes being more closed and angular. One specimen also had conspicuous striations on the pronotal disc. The pattern on the pronotal expansion is constant, but the pattern is unique to each individual and asymmetrical ( Fig. 2d View FIGURE 2 ). The pattern of the spine-like carinae is also unique to each individual.

Sexual dimorphism. No notable sexual dimorphism. The elytral epipleura is slightly wider in females. The sizes of males and females are very variable and may overlap between the sexes.

Etymology. From Latin alveolaris meaning alveolar due to the reticulated or bubble-shaped design of the pronotal expansion.

Distribution, habitat and biological observations. Know only from the type locality in the National Park Pan de Azúcar. D. alveolaris sp. nov. inhabit in quebradas in the coastal Atacama Desert between the 100–500 m asl ( Fig. 1b View FIGURE 1 ). All specimens were collected during the night associated to sandy soil in rodent burrows or walking between bushes/cacti. In controlled conditions, the complete metamorphosis took about eleven months. The larvae come to the surface to molt leaving the exuvia on the surface (see Fig. 1d View FIGURE 1 ). The state of pupation lasted ~30 days.

Genetic comparison. Partial fragments of 725 bp to 815 bp of COI were obtained. We found two haplotypes of COI gene in D. alveolaris sp. nov. with a 0.2% genetic distance. The genetic distance of COI between D. alveolaris sp. nov. and other species included in this study was greater than 4%. D. alveolaris sp. nov. is genetically closer to D. costalenis (4.5–4.7%) than D. aff. bicarintus (5.8%) or D. reticulatus (6.1%) (see Table 1).