Hygronemobius caxiuana Santos, Cadena-Castañeda & Tavares sp. nov.

urn:lsid:zoobank.org:act: 30C1DF67-2AC9-429A-BFC6-6D0A3228F28C

(Figs. 1–6, Map 1)

Type material. Holotype. Male. Brasil [Brazil], Pará, Melgaço, FLONA Caxiuanã, ECFPn-ESECAFLOR; 1°43'35"S, 51°26'36"W; III.2012; D.A. Cunha leg. Repository: MPEG.

Paratypes. 15 males and 47 females. Same data as the holotype, but I.2012 (MPEG) . 95 males and 43 females. Same data as the holotype, but II.2012 (MPEG) . 108 males and 129 females. Same data as the holotype, but III.2012 (MPEG) . 2 males and 4 females. Same data as the holotype, but III.2011 (MPEG) . 94 males and 90 females. Same data as the holotype, but IV.2012 (MPEG) . 57 males and 62 females. Same data as the holotype, but V.2012 (MPEG) . 58 males and 85 females. Same data as the holotype, but VI.2012 (MPEG) . 1 female. Same data as the holotype, but VI.2011 . 55 males and 93 females. Same data as the holotype, but VII.2012 (MPEG) . 33 males and 31 females. Same data as the holotype, but VII.2011 (MPEG) . 41 males and 49 females. Same data as the holotype, but VIII.2012 (MPEG) . 11 males and 34 females. Same data as the holotype, but IX.2012 (MPEG) . 2 females. Same data as the holotype, but IX.2011 (MPEG) . 62 males and 62 females. Same data as the holotype, but XI.2011 (MPEG) . 5 males and 1 female. Same data as the holotype, but XI.2012 (INPA) . 3 males and 9 females. Same data as the holotype, but XII.2011 (BOTU) .

Etymology. The epithet refers to the type locality of the species, Floresta Nacional de Caxiuanã, in the municipality of Melgaço, Pará. The name should be treated as a noun in apposition.

Suplemmentary material. 102 males and 115 females. Same data as the holotype, but collection date unknown (MPEG) . 2 males and 1 female. Same data as the holotype, but collected in November of an unknown year (MPEG) .

Diagnosis. This species clearly belongs to the benoisti species group due to its body coloration pattern, which is predominantly brown with abundant light and dark spots (Figs. 1A–C), ochre palps (Fig. 1E), and male genitalia with truncated and broad apical lobe located dorsally on the pseudepiphallus, making it difficult to distinguish from the pseudepiphallic sclerite (Fig. 5A). However, this species differs from Hygronemobius diplagion Desutter-Grandcolas, 1993 in the female abdominal coloration, with the lateral portion of the first tergite, the second and third, almost all the fifth, the middle part of the seventh to ninth tergites, and supra-anal plat ochre (Fig. 6B) [in H. diplagion, abdomen almost entirely darkened, except for the lateral portion of the first tergite, tergites two and three, the middle portion of fifth and two spots on the seventh tergite]. Additionally, the male genitalia median lobe is broader, nearly as wide as long [narrower and longer than wide in H. diplagion], with a rough distal portion covered in small bristle-like structures resembling punctuations or papillae (Fig. 5A) [smooth in H. diplagion], and the endophallic sclerite with the postero-lateral portion separated from the mid-posterior portion (Fig. 5A, B) [continuous in H. diplagion]; from Hygronemobius tetraplagion Desutter-Grandcolas, 1993 in having a truncated apical lobe instead of an acuminate one (Fig. 5A); from Hygronemobius elegans Desutter-Grandcolas, 1993 by its reduced ectophallic fold (Fig. 5C) [notably well-developed in H. elegans]; and from Hygronemobius benoisti Chopard, 1920b by the absence of elongated bristles on the pseudepiphallic sclerite, showing only very reduced bristles resembling punctuations or papillae (Fig. 5A) [in H. benoisti, bristles are long and easily distinguishable].

Description. Head, in frontal view, triangular, with well-developed eyes, taller than wide, as tall as half the height of the head, and the antennal orbit close to the lower margin of the eyes (Fig. 1E). Coloration of the cephalic capsule similar in tone to the clypeus and labrum (slightly lighter), with a mixed pattern of light and dark brown (Fig. 1E). Reticulated spots formed by dark brown punctuations, weakly interconnected, extending laterally from the lower area of the eyes across the gena to the proximal portion of the mandible (Figs. 1D–E). In lateral view, a shaded dark brown reticulated spot surrounds the eyes, extending from the gena to the vertex (Fig. 1D). Post-gena uniformly yellowish (Fig. 1D). Maxillary palp with the first two segments subequal, cylindrical, yellowish in color, and whitish distally; third segment longer than the two previous ones combined, subcylindrical, narrower, and whiter than the preceding and succeeding segments; fourth conical, smaller, and slightly darker than the third; fifth conical, distally rounded, longer than any previous segment, and yellowish (Fig. 1F).

Thorax. Pronotum, in dorsal view, rectangular, with anterior and posterior margins nearly straight. Coloration light brown with irregular eye spots on the median posterior half (Figs. 1B; 2A). AS formed by three almost parallel macrochaetae; MSG formed by three macrochaetae, being two almost parallel and one obliquely positioned to the middle one; PS formed by seven macrochaetae arranged in a curved line from the posterior portion of the pronotal disc eye spots to the anterolateral portion and two mesochaetae branching from the fourth macrochaeta (Figs. 2A–B); In lateral view, lateral lobe longer than tall, with sinuous ventral margin bearing a medial concavity and a dark triangular patch narrowing towards the anterior margin (Figs. 1A, D; 2A, C). LS formed by four macrochaetae and one mesochaeta following the oblique border of the lateral lobe mark (Figs. 2C–D). Prosternum reduced, with concave dark brown spots; mesosternum rectangular, with rounded corners and slightly darker anterior portion; and metasternum hexagonal, with slightly darkened anterior edges. Mesosternum and metasternum setose (Fig. 1G).

Wings. Tegmina light brown with whitish spots in the anal, postcubital, and harp regions and at the distal apex of the wing, radiating from the cubital-anal region and extending along the entire length of the medial + cubital-anal vein. Aa+PCup veins faintly visible. Tegmina oval, longer than wide (Fig. 3A). In lateral view, narrow and elongated, with an evident curvature in the first C+Sc vein (Fig. 3B, white circle). Stridulatory file with 45 teeth (N = 1, Fig. 3C).

Legs ochre, with brownish spots, conspicuous setae (macrosetae), and pubescent surface covered with small setae (Figs. 4A–F). All tibia and tarsi with brown spots intercalated with lither rings (Figs. 4A–F). First pair of legs with two spurs and with tympanum only on the outer side (Figs. 4A–B). Middle legs similar to the anterior ones (Figs. 4C–D). Hind legs robust, with three dorsal spurs on each margin, two apical on the inner margin, and three on the outer margin (Figs. 4E–F).

Abdomen, in dorsal view, brownish with a continuous and irregular ochre macule ranging from the sixth segment to the supra-anal plate, forming a whitish triangle (Figs. 1B; 4G). In ventral view, sternites dark brown, with whitish and circular spots, laterally located on the medio-distal portions of the segments (Fig. 1C). Supra-anal plate with widely convex posterior border (Fig. 4G). Subgenital plate, in ventral view, darkened, with two whitish spots on the posterolateral margin, longer than wide, with a slightly incised posterior border (Fig. 4H). In lateral view, longer than high, with a slightly curved ventral surface (Fig. 4I).

Phallic complex. Pseudepiphallic apical lobes truncated and laterally covered by the median lobes (Figs. 5A, D); membranous distally, slightly longer than wide, hyaline, with apex bearing small setae and a brief sinus between the lobes (Fig. 5A); laterally barely visible, covered by the median lobe (Fig. 5D). Pseudepiphallic median lobes well-sclerotized and anteriorly curved, with three distal lobes (Fig. 5A–C). Ectophallic apodemes thin. Endophallic sclerite central part connected to lateral appendages only distally and medio-proximally clearly separated; lateral appendages heart-shaped (Figs. 5A–B). Endophallic apodeme reduced (Fig. 5B). Rami straight and thin (Fig. 5A– B). Ectophallic fold reduced, hyaline, and poorly sclerotized (Fig. 5D).

Female. Wings reduced (Fig. 6A). Base of the pronotal disc larger than males (Fig. 6B). Abdominal tergites spotted in dark brown, with the lateral portion of the first tergite, the second and third, almost all the fifth, the middle part of the seven to ninth tergites, and supra-anal plat ochre, the remaining tergites spotted in brown (Fig. 6B). Ovipositor slightly upcurved (Fig. 6D), light brown ventrally, and darkening dorsally and toward the apex, which bears very small denticulations (Figs. 6E–F). Tenth tergite setose, very small, with rounded posterior margin and a slightly whitish spot giving the impression of a division in the tergite (Fig. 6G). Subgenital plate whitish, almost yellowish, and with a slightly darkened brown oval spot (Fig. 6I); in ventral view, wider than long and emarginated (Fig. 6H); in lateral view, longer than tall, with rounded posterior margin (Fig. 6H).

Measurements (mm).

Males. TL: 6.6–7.1; PL: 1.1–1.9; PW: 1.1–1.9; Tg: 2.7–3.3; HF: 3.7–4.3; HT: 2.1–3.5.

Females. TL: 6.7–8.4; PL: 1.1–2.0; PW: 1.2–2.0; Tg: 0.6–1.2; HF: 3.4–4.1; HT: 3.0–3.7; Ov: 2.9–3.3.

Distribution. This species is known only for its type locality, in the Floresta Nacional de Caxiuanã, Melgaço, Pará State (Map 1).