Halictoxenos fortunatus, Quintos-Andrade & Valenzuela-González, 2024

Quintos-Andrade, Gerardo & Valenzuela-González, Jorge E., 2024, First record of Halictoxenos Pierce (Strepsiptera: Stylopidae) from Mexico with the description of a new species parasite of Lasioglossum exiguum (Smith) (Hymenoptera: Halictidae), Zootaxa 5514 (2), pp. 157-168 : 160-163

Halictoxenos fortunatus sp. nov.

http://zoobank.org/ 4D85D2DB-3C2F-4367-9044-740E7C585153

Diagnosis. The male of Halictoxenos fortunatus is similar to those of H. jonesi and H. schwarzi , but they differ from these and other species by a combination of characters: Body covered with dark setae; occipital area projected in the form of a protuberance; maxillary palp with a thin tip and an homogeneous setae pattern; transparent wings without setae; veins CuA2 and CuP present, the latter touching the lower margin; aedeagus with the spine arched in an approximate 120° angle, a thin and curved acumen.

The cephalothorax of the female of H. fortunatus presents characteristics associated with the type material recognized as H. crawfordi , but it differs from this and other species due to a combination of several characters: rhomboid body as large as wide; cuticle highly alveolate-tesselate, alveolate-aciculate in the prosternum and mesosternum; obtuse posterior margins; head capsule with a rounded margin; arched mandibles in a 90° angle that does not protrude beyond the margin of the head capsule; mandibular tooth present; brood opening arched and not protuberant; mesosternum with transverse, conspicuous and protuberant asymmetrical papillae with a C-shaped orifice; constriction of the first segment equal to ¾ the greatest width of the body.

The larva of H. fortunatus is similar to that of H. crawfordi , but it differs from the latter by presenting a straight body; dorsal segments of the head and the thorax without central setae and ninth abdominal segment without lateral setae.

Male

( Figs. 2C – 3 )

Holotype description. Total length. 2.28 mm. Coloration. Dark with some lightened parts like mandibles, antennal inserts, base of the antennal segments, base of the halteres, wings, lateral regions of the abdomen and tarsomere pads. Head. Head width. 0.62 mm. Head length: 0.15 mm. Head wider than long. Dark eyes with setae between the facets. 44 facets per eye. Extended forehead, depressed between the antennae. Head covered with setae. Occipital region projected in the form of a protuberance. Mouth Parts. ( Fig. 3 BC). Maxillary base length. 0.12 mm. Maxillary palp length. 0.14 mm. Mandibular length. 0.21 mm. Straight mandibles, slightly elevated, flattened tips, not very thick. Mandibular bases immersed in the genal area. The mandibles cross at the tips. Maxillary base as long as the maxillary palp, wide in the apex with elongated setae. Maxillary palp blunt-like, inserted bellow the apex of the base, slightly widened in the middle and covered with setae as long as the base. Antennae. Covered with setae. Segments 3 and 4 are flabellate and with sensorial pores. S1 campanulate, wider than S2. S3 as long as S4, blunt-like, concave at the base. S4 similar to S 3 in the apex, slightly compact at the base. Segment length. S1: 0.09 mm. S2: 0.06 mm. S3: 0.39 mm. S4: 0.39 mm. Thorax. Scutum pronounced and rounded apically, rhomboid. Scutal processes not very pronounced, as wide as the scutum. Triangular scutellum, prominent on the back. Straight postlumbium in the front, semicircular in the posterior. Elongated pronotum, truncated at the apex. Wings. ( Fig. 3A ). Halter length. 0.42 mm. Apex circular and swollen, the rest flat, with a protuberance in the base and a medium dark fold. Hyaline hind wing, with marked veins. R 1 curved, close to the stigma and thickened, encompassing more than 3/4 of the anterior margin of the wing. R 2 thickened, smaller than R 1 and closer to it, touching the alar margin. R 3 curved, twice as long as R 2, touching the wing margin. R 4 continue to R 5, slightly curved and touching the wing margin. MA straight, close to the wing margin. CuA1 parallel to MA. CuA2 straight, as thick as CuA1, without touching the wing margin. CuP slightly curved, thickened, and close to the wing margin. Legs. ( Fig. 3E ). Trochanter present in hind legs. Legs covered with setae. Femurs 1 and 2 cylindrical, the third one dilated at the base. Absent claws. Tarsi with pale adherent pads. Length of each leg segment: Front femur: 0.33 mm. Middle femur: 0.21 mm. Hind femur: 21 mm. Front tibia: 0.22 mm. Middle tibia: 0.19 mm. Hind tibia: 0.23 mm. Frontal tarsi: 0.22 mm. Middle tarsi: 0.25 mm. Hind tarsi: 0.27 mm. Abdomen. Swollen, tergites 1-9 lightened, each one with two brown spots. T 10 truncated at the apex. Sternites darker and wider than the tergites. Aedeagus. ( Fig. 3D ). Total length. 0.09 mm. Spike length. 0.02 mm. Apex thinner than the base, arched at 90° in relation to the body. Spine present, erect. Ventral spine curved and sharp at the tip.

Male cephalotheca

( Fig. 2B )

Description. Length: 0.54 mm. Width: 0.71 mm. Form and coloration. Elliptical, slightly compressed along. Central part prominent at side view. Pale yellow coloring. Labrum and mandibles more intense than the rest of the capsule. Capsule. Eyes paler than the entire capsule. Non-visible corneal lenses. Pale genal area and around the eyes. Pale clypeus, elevated in inversed U-shape, smooth. Frontal area different from the clypeus. Occipital bulge absent. Genal area 1-1.5x diameter of the vestigial antennae. Antennae and supraantennal area. Antennal vestige present, pale. Toruli complete. Pale supraantennal field, not protuberant nor delimited. Labrum. Protuberant, pale with an intense margin. Prolonged ventral field. Mandible. Pale. Arched towards the middle area of the clypeus. Mandibular tooth present, sharp and located at the top. Maxilla. Pale. Fused with the capsule, noticeable as longitudinal striations. Vestigial palp present. Labium and hypopharynx. Pale. Not prominent. Mouth opening. U-shaped.

Female cephalothorax

( Fig. 2A – 4 )

Description. Total length: 0.41–0.48 mm. Total width: 0.45–0.47 mm. Form, structure and coloration. Pentagonal, slightly wider than long. Trapezoidal head margin, slightly elongated at the tip. Contracted mesothoracic margin, wider than the head. Wide thorax, rounded margins. Cuticle highly alveolate-tesselate, alveolate-aciculate in the prosternum and mesosternum, wrinkled in the mandibles and surrounding areas ( Fig.4 AC). Pale orange body, central part of the metasternum and first abdominal segment darkened. Head capsule. Head length: 0.18–0.23 mm. Pale yellow to pale orange coloring in all the surfaces. Clypeus and labrum delimited by a little pronounced suture. Flattened clypeus with sensilla. Frontal cuticle flattened, covered with scattered setae. Brood aperture delimited from the mesosternum by a transverse pattern of long aciculate microsculpture ( Fig.4 AB). Sensillar supraantennal field and antenna. Inconspicuous. Vestige of antenna not visible. Labrum. Flattened and with sensilla. Mandible. Arched at 90°. Mandible bulge prominent, with sensilla, mandible enclosed into mandibular capsule. Reticulated mandible with longitudinal striations and sensilla. Mandibular tooth present behind the mandible and surrounded by spines, angulation variable, truncate at the apex ( Fig.4 BG). Maxilla. Fused with the labial area, visible as dim striations. Palp vestige present below mandibles ( Fig.4F ). Labium. Delimited between the maxilla. Shaped as longitudinal striations with scattered sensilla. Mouth opening. Straight or U-shaped. Sclerotized laterals, slightly dark. Thorax. Borders of thoracic segments delimited by little pronounced sutures and changes in the sculpture. Indistinct in dorsal view. Prosternum with an alveolate-aciculate sculpture without setae. Mesosternum with alveolate-aciculate sculpture, slight irregular striations and between 5 and 9 asymmetrical papillae with C-shaped orifices. Protuberant papillae visible in lateral or three quarters view; papillae wrinkled distally ( Fig.4 CDE). Gland system conspicuous in light microscope ( Fig.2A ). Sculpture of the metasternum similar to prosternum. Prosternum, mesosternum and laterals of the metasternum with a pale orange coloring. Central area of the metasternum dark. First abdominal segment and spiracles. Pale lateral coloring, conspicuous spiracles in light microscope, depressed at the laterals and delimited in an extension of the metasternum.

Figures

FIGURE 2. A) Halictoxenos fortunatus sp. nov. female cephalothorax. B) Halictoxenos fortunatus sp. nov. male cephalotheca. C) Halictoxenos fortunatus sp. nov. male habitus. Abbreviations: a—vestigial antenna, bo—birth opening, cl—clypeus, cla— clypeal area, coe—compound eye, fi—frontal impression, gn—gena, hyp—hypopharynx, lehc—lateral extension of the head capsule, lf—dorsal field of labral area, md—mandible, mpap—mesosternal papillae, mst—mesosternum, mtst—metasternum, mx—maxilla, os—mouth opening, pst—prosternum, sI—first sternite, sp—spiracle, ssf—supra-antennal sensillary field. Scale bar= 0.5mm.

FIGURE 3. Halictoxenos fortunatus sp. nov. male illustration. A) Male habitus showing wing venation. B) Maxilla. C) Mandible. D) Genitalia. E) Legs: (I) prothoracic leg, (II) mesothoracic and (III) metathoracic leg.

FIGURE 4. Halictoxenos fortunatus sp. nov. SEM of female cephalothorax. A) Ventral habitus. B) Mouthparts and base of prosternum. C) Mesosternum in three quarters view showing protruding mesosternal papillae. D) Detail of C-shaped orifices of central mesosternal papilla. E) Detail of distal mesosternal papillae, showing distinct morphology. F) Detail of vestige of maxillary palp. G) Detail of right mandible.Abbreviations: bo—birth opening, cla—clypeal area, cll—clypeal lobe, dlf—dorsal field of labral area, lba—labial area, lf—labral field, md—mandible, mdb—mandibular bulge, mdbs—sensillum of mandibular bulge, mdc—mandibular capsule, mdt—mandibular tooth, mdts—spine of mandibular tooth, mpap—mesosternal papillae, mst—mesosternum, mtst—metasternum, mxp—vestige of maxillary palp, os—mouth opening, pst—prosternum, sI—first abdominal sternite, vlf—ventral field of labral area.