Arisemus mixtecus Ibáñez-Bernal & Durán-Luz, 2025

Arisemus mixtecus Ibáñez-Bernal & Durán-Luz , sp. nov.

( Figs. 16–28 View FIGURES 16−20 View FIGURES 21−22 View FIGURES 23−28 )

Diagnosis. Arisemus mixtecus is distinguished from other species of the genus by the following combination of characters: antennae with scape slightly longer than pedicel; palpus reaching flagellomere 10; wing infuscate with dark spots on vein apices. Male: anepisternum without scent organ; aedeagus asymmetric; gonostylus simple without cluster of setae; gonocoxite anterior condyles elliptical; ejaculatory apodeme anteriorly truncate; parameres seen as triangular sclerotizations in dorsal view and a hyaline parameral sheath that covers dorsally the basal half of the bipartite aedeagus, of which one is a simple branch externally curved and pointed, and the other branch is externally curved and pointed and with a short lobe near its middle. Female: genital plate with lateral margins near straight, convergent posteriorly to form a long neck; hypovalvae nearly triangular, the intervalvae posterior margin nearly triangular.

Male description ( Figs. 16–22 View FIGURES 16−20 View FIGURES 21−22 ). Head slightly oval in frontal view, eyes contiguous, eye bridge with three rows of facets. Frontal patch of alveoli divided in center. Palpus long, reaching flagellomere 10, proportion of palpal segments: 1.00: 1.14: 1.43: 2.00 ( Fig. 16 View FIGURES 16−20 ). Antennae with scape 1.3 times larger than pedicel; flagellum with 14 flagellomeres, flagellomeres 1–11 nodiform, the three apical flagellomeres reduced, the last one with a small apiculus; flagellomeres 1–2 without ascoids, flagellomere 3 with only one digitiform ascoid, flagellomeres 4–11 each with a pair of digitiform ascoids ( Fig. 16–18 View FIGURES 16−20 ). Mouthparts with inverted Y-shaped sclerite; each labellum with 5 tooth-like sensilla on the internal margin ( Fig. 19 View FIGURES 16−20 ).

Wing 2.9 times longer than width, infuscate with dark spots on vein apices and base of R 5; radial and medial forks complete, almost at the same level; radial sector pectinate, R 2+3 short; CuA 2 not reaching wing margin ( Fig. 20 View FIGURES 16−20 ). Thorax without scent organs on anepisternum.

Aedeagus asymmetric, ejaculatory apodeme expanded anteriorly, truncate and with a shallow concavity, larger than aedeagus; aedeagus extends beyond gonocoxite apex; aedeagus with two externally curved branches that end in point, one with an external lobe near its middle; parameres as triangular sclerotizations and a hyaline parameral sheath that covers the basal half of the bipartite aedeagus. Gonocoxite as long as gonostylus, homogeneously pilose and with an internal patch of 5–6 small setae. Gonostylus simple, homogeneously pilose, tapering toward apex ( Fig. 21 View FIGURES 21−22 ). Epandrium wider than long, with a wide foramen near basal margin; hypopod larger than epandrium, with an apical spatulate tenaculum; epiproct triangular, with setae on the distal region; posterior margin of hypoproct rounded, pilose ( Fig. 22 View FIGURES 21−22 ).

Measurements. (n=2). Head width: 0.335 (0.33–0.34); head length: 0.360; length from vertex to the dorsal margin of eye: 0.145 (0.14–0.15); labrum length: 0.090; proboscis length: 0.100; palpus length: 0.370 (0.35–0.39); antenna length: 0.660, n=1; wing length: 1.460 (1.34–1.58); wing width: 0.510 (0.47–0.55); epandrium width: 0.140; epandrium maximal length: 0.170; hypopod length: 0.220 (0.21–0.23); gonocoxite length: 0.115 (0.11–0.12); gonostylus length: 0.110; aedeagus length: 0.200.

Female description ( Figs. 23–28 View FIGURES 23−28 ). Like male, except by the following characteristics: palp reaching flagellomere 13, proportion of palpal segments: 1.00: 1.14: 1.43: 2.43 ( Fig. 23 View FIGURES 23−28 ). Antenna with scape 2.0 times the length of pedicel; flagellomere 1 with no ascoids, flagellomere 2 with one small ascoid, and flagellomeres 3–11 with a pair of digitiform ascoids (Fig. 24,25). Wing as long as 3.1 times its width ( Fig. 26 View FIGURES 23−28 ).

Genital plate pilose, calyx-like, slightly longer than wide, with lateral margins nearly straight converging to the long neck at base of the apical lobes (hypovalvae); Hypovalvae separated by a shallow concavity; chitinous arch not reaching apical margin ( Fig. 27, 28 View FIGURES 23−28 ). Ventral receptacle with a pair of semispherical structures anteriorly, which are supported by wide and strong sclerotized outwards curved rods. Genital chamber with a central hole and two groups of three spiniform setae near it, with an elongated membranous plate ( Fig. 27 View FIGURES 23−28 ). Cerci 1.2 times longer than genital plate ( Fig. 28 View FIGURES 23−28 ).

Measurements. (n=6). Head width: 0.368 (0.35–0.38); head length: 0.400 (0.39–0.42); length from vertex to the dorsal margin of eye: 0.173 (0.15–0.19); labrum length: 0.107 (0.10–0.11); proboscis length: 0.118 (0.11–0.12); palpus length: 0.443 (0.42–0.48); antenna length: 0.665 (0.65–0.68) n=2; wing length: 1.700 (1.59–1.85); wing width: 0.552 (0.50–0.60); basal width of genital plate: 0.202 (0.19–0.21); total length of genital plate: 0.225 (0.22– 0.24); cerci length: 0.280 (0.26–0.30).

Material examined. Holotype ♂: Mexico, Puebla, Jolalpan, Rancho El Salado (18° 20'35.3"N, 98° 57'19.1"W, altitude 941 m.), CDC light trap, J. Durán-Luz, col. 02-v-2017, 1 ♂ GoogleMaps . Paratypes 1 ♂, 6 ♀: same data as holotype, except: 02-v-2015, 1 ♀ GoogleMaps ; 30-iv-2017, 3 ♀ ; Malaise trap (18° 20'20.6"N, 98° 57'15.7"W, altitude 937 m), 12–14-ii-2017, 1 ♀ GoogleMaps .

Type locality. Mexico, Puebla, Jolalpan, Rancho El Salado.

Etymology. The term mixtecus , refers that is native of the Mixteca. This is a cultural region in western Oaxaca and neighboring portions of Puebla, and Guerrero, in south-central Mexico, home of the Mixtec people, and where this species was collected.

Comments. Arisemus mixtecus resembles A. aenigmaticus Quate & Brown, 2004 and A. grabhamana (Dyar) by the general aspect of terminalia. However, the antepronotum of A. aenigmaticus has a fig-shaped scent organ in front of anterior spiracle, the gonostylus is sinuous with a patch of setae on the base of the external margin, and the ejaculatory apodeme is rounded, whereas A. grabhamana present a scent organ like tenuous sacs with a dark central body and the anterior margin of ejaculatory apodeme rounded.