Hyleotermes, Cuezzo & Scheffrahn & Constantino, 2022

Cuezzo, Carolina, Scheffrahn, Rudolf H. & Constantino, Reginaldo, 2022, Revised systematic position of Nasutitermes brevipilus Emerson, 1925 (Isoptera Termitidae: Nasutitermitinae) and the designation of Hyleotermes gen. nov., Zootaxa 5195 (1), pp. 73-86 : 78-79

Hyleotermes gen. nov.

Type-species. Nasutitermes brevipilus Emerson, 1925 .

Etymology. From the Latin word hylaeus (Greek hylaios), from the forest, meaning a forest termite.

Included species. Hyleotermes brevipilus ( Emerson, 1925)

Diagnosis. The head capsule Hyleotermes soldier is ovoid in dorsal view, has a long cylindrical nasus, lacks a constriction and long setae, and is covered with microscopic hairs. The mixed segment of the slightly dimorphic worker caste is very short and the enteric valve has six cushions of differing sizes, with each adorned with a few to dozens of narrow spines on conical bases.

Description

Imago. Eyes large slightly ovoid; ocelli large and elliptical, about as large as antennal socket. Postclypeus slightly arched in profile; midline conspicuous and slightly depressed; anterior margin nearly straight; posterior margin convex. Fontanelle conspicuous, slit-shaped. Epicranial suture faint. Antenna with 15 articles. Mandibular dentition similar to those of worker type 2. Pronotum trapezoidal in dorsal view; anterior and posterior margins nearly rectate. Posterior margin of meso- and metanotum deeply and broadly emarginated; posterolateral corners of meso- and metanotum rounded. Tibial spurs 2:2:2.

Soldier. Monomorphic. In dorsal view, head capsule longer than wide, not constricted. Nasus elongate, subcylindrical. Head capsule, legs, and thoracic sclerites covered with dense short and rather thick hairs. Mandibles with small but well-defined ‘points’. Antenna with 12 articles. Postclypeus not convex in profile. Labrum shorter than wide, with rounded anterior margin, parallel lateral margins, and rounded anterior corners. Pronotum with anterior lobe as developed as the posterior one, forming an obtuse angle between them. Procoxa conical, not forming a keel and without a hump on the anterior surface. Tibial spurs 2:2:2.

Worker. Dimorphic, but both types similar in size. Left mandible of type 1 ( Fig. 3A ) with a narrow gap between the third marginal tooth (M3) and the molar prominence ( MP), a darker colored, subtrapezoidal head capsule, and narrower pronotum with its anterior lobe larger than the posterior one. Left mandible of type 2 ( Fig. 3B ) with a broad gap, a slightly lighter colored head capsule with more convex sides, and a wider pronotum with the anterior lobe about the same size as the posterior one. Both workers with fontanelle situated in the posterior half of the head capsule, pale and slightly depressed, in profile view. Postclypeus not inflated. Antenna with 13 articles. Tibial spurs 2:2:2. Left mandible of both types with apical tooth larger than M1; posterior margin of apical tooth slightly concave; acute angle between posterior margin of apical tooth and anterior margin of M1; posterior margin of M1 sinuous; M3 short but distinct, separated from the molar prominence by a V-shaped gap in worker type I and a broad gap in worker type 2; M4 short, hidden beneath molar prominence; molar prominence concave, with faint ridges. Right mandible with apical tooth larger than M1; M3 reduced, with rounded tip; posterior margin of M3 concave; molar plate concave with faint ridges; basal notch well-defined, but narrow in type 2 workers.

Gut Coiling ( Figs. 5A–F ). Crop slightly more developed than gizzard, partially visible in left lateral view. Mesenteron passing through right side of the abdomen to join the first proctodeal segment (P1) before reaching medial line in ventral view. Very short mixed segment; mesenteric tongue external to the mesenteric arc, not constricted proximally, lateral margins converging distally. Malpighian tubules arranged in two adjacent pairs, but attached on the inner face of the mesenteric arc individually at mesenteron–proctodeum junction; tubules slightly dilated at the attachment point ( Fig. 5E ). P1 tubular, slightly larger than the mesenteron, reaching left side of abdomen. Distal part of P3 protruding through mesenteric arc, very prominent in dorsal view, notoriously dislocated to left; isthmus conspicuous. Dorsal torsion well developed. ‘U-turn’ tubular, slightly dilated, visible in lateral right view ( Fig. 5F ). Distal colon tubular, narrow than the proximal part and joining the rectum in dorsal view.

Internal compartment ornamentation. Crop cuticle with pectinate scales. Gizzard ( Figs. 6A–C ) with completely sclerotized cuticular armature (hexaradial symmetry); pulvillar belt more developed than columnar belt, pulvilli I more developed than pulvilli II, both with their entire surface covered with long aciculiform spines; columns I and II ornamented with short spines. Cuticle of P1 armed with spines only at mesenteron–proctodeum junction. Armature of the enteric valve weakly sclerotized ( Fig. 6D ), organized in two rings; anterior ring (or upper ring, closest to P1) with 10-20 small spines barely organized in three cushions; posterior ring (or lower ring, closest to P3) with six subconical cushions varying in size; each cushion covered with a few to thirty narrow spines projecting from basal scales ( Fig. 7A ).

Comparisons. The Hyleotermes brevipilus soldier is closest to soldiers of Ereymatermes Constantino, 1991 , and Subulitermes Holmgren, 1910 in that all three are small, yellowish in coloration, and have cylindrical nasi. Of these, only the headcapsules of H. brevipilus , S. constricticeps, Constantino, 1991 , and S. microsoma (Silvestri, 1903) lack long setae. Subulitermes constricticeps and S. microsoma are much smaller (mean head width ca. 0.6 mm). The worker enteric valve of H. brevipilus is diagnostic and differs those of Ereymatermes ( Constantino 1991) and Subulitermes ( Fontes 1986) . The following worker characters are distinct in Nasutitermes s. str.: EVA with pointed scales on large and small cushions, with trailing columns of scales toward posterior ( Fig. 7B ); molar plate narrow, straight, with well-developed ridges; each mandible with a short apical tooth and larger marginal teeth; mixed segment very long; enteric valve unsclerotized, with minute spines. Also, in Nasutitermes female workers are conspicuously larger than male workers. In all genera of Nasutitermes s. str., the worker mandibles have conspicuous molar ridges, and most of them have a long mixed segment.

Figures

FIGURE 3. Worker mandibles of Hyleotermes brevipilus, comb. nov. A, type 1 (narrow gap); B, type 2 (broad gap). Gap is between the third marginal tooth (M3) and molar prominence (MP) of left mandibles.

FIGURE 5. Gut morphology of the worker of Hyleotermes brevipilus, comb. nov. gut in situ; A, dorsal; B, left; C, ventral; D, right; E, mixed segment and attachment of Malpighian tubes; F, segment of proctodeum (P3–P4) showing the isthmus.

FIGURE 6. Gizzard and enteric valve of the worker of Hyleotermes brevipilus, comb. nov. A, complete gizzard armature, showing columnar and pulvillar belts; B, detail of column I, ornamented with scales; C, detail of pulvillus I with their entire surface covered with long aciculiform spines.

FIGURE 7. Worker enteric valve armature of A, Hyleotermes brevipilus comb. nov.; B, Nasutermes corniger from Panama (UFTC no. PN379).