Plutogeophilus jurupariquibaba, Bonato & Ferreira, 2023

Bonato, Lucio & Ferreira, Rodrigo Lopes, 2023, Assessing troglomorphic and phylogenetically informative traits in troglobionts: a new cave-dwelling centipede illuminates the evolution of a soil-dwelling lineage (Chilopoda: Geophilidae), Organisms Diversity & Evolution (New York, N. Y.) 23 (4), pp. 833-856 : 853-854

Description of holotype of Plutogeophilus jurupariquibaba sp.n.

ISLA 11879 ( Figs. 3 , 4a–g).

General features. Body depressed and almost uniformly wide along the trunk, only slightly narrowing backward. Color (in ethanol) uniformly brownish yellow, head and forcipular segment slightly darker.

Cephalic capsule. Cephalic plate sub-quadrate, about as long as wide, lateral margins slightly narrowing more forward than backward; scutes approximately isometric and up to 10 μm wide in the anterior half of the cephalic plate, only slightly elongated longitudinally in the posterior half; transverse suture absent; setae up to ca. 80 μm long. Clypeus ca. 2.3 times as wide as long, with lateral margins complete; uniformly areolate, the scutes being up to 10 μm wide, with a single medial clypeal area, distinctly projecting ventrally; 3 pairs of setae, including one inside the clypeal area, one anterior and one latero-posterior. Pleurites uniformly areolate, without setae; an additional suture across the anterior part of the pleurite, almost reaching the lateral margin of the cephalic plate. Intermediate part of labrum ca. 1.5 times as wide as long, bearing ca. 8 stout tubercles, which are relatively sclerotized, stout but with a very short apical spine. Lateral parts of labrum far apart from each other, each bearing a row of a dozen marginal bristles, which are poorly sclerotized.

Antennae. Slender, ca. 3.8 times as long as the head width. Intermediate articles up to ca. 2.0 times as long as wide. Article XIV ca. 2.4 times as long as wide, ca. 1.6 times as long as article XIII. Setae gradually denser and shorter from the basal articles to the distal ones, both ventrally and dorsally, up to 80 μm long on article I but less than 50 μm long on article XIV. Apical sensilla ca. 15 μm long, spear-like, without projections, distinctly narrowing at about the mid-length. Club-like sensilla ca. 10 μm long, only on article XIV, grouped on the distal parts of both the internal and external sides. Three longitudinal rows of 1–5 proprioceptive spine-like sensilla at the bases of the antennal articles, approximately dorsal, ventro-internal, and ventroexternal; ventral rows poorly detectable on articles I–II; rows reduced to 0–1 sensilla on antennal articles VI, X, and XIV. A few sensilla, similar to the apical ones, up to 5 μm long, on both dorso-external and ventro-internal position, close to the distal margin of articles V, IX, and XIII; no distinctly darker spear-like sensilla (type “c” in Pereira et al., 2000) .

Mandibles. A single pectinate lamella, with ca. 25 teeth, on each mandible; most teeth elongate, more than 4 times as long as wide at the basis.

First maxillae. Coxosternite entire, without mid-longitudinal sulcus, with 5 setae. Coxal projection sub-triangular, wider than long, bearing 8 setae. Telopodite composed of two articles, the distal one with 4–5 setae. A pair of short, round lappets on the basal articles only, fully concealed from below.

Second maxillae. Coxosternite remarkably shortening mid-longitudinally (<0.1 of the maximum length), the anterior margin deeply angulated and with approximately straight converging sides, the intermediate part weakly sclerotized and with mid-longitudinally sulcus; 23–24 setae, all in the medial part or close to the anterior margin; no anterior projections; metameric pores featuring as transverse slits, without statuminia or other distinctly sclerotized elements. Telopodite composed of three articles, only slightly narrowing towards the tip; 2–3 short ventral setae on the basal article, 1–2 mesal setae on the intermediate article, ca. 14 long setae on the distal article, most of which on the ventral side; pretarsus in shape of an elongate claw, ca. 0.8 times as long as the distal article, and ca. 4.5 times as long as wide at the basis, subconic and slightly bent; 3 pore-like sensilla on each pretarsus, one on the antero-dorsal side and the other two on the ventral side.

Forcipular segment. Tergite subtrapezoidal, ca. 2.3 times as wide as long, with lateral margins strongly converging forward, ca. 0.8 times as wide as the subsequent tergite, partially covered by both the cephalic plate and the subsequent tergite. Pleurites without scapular ridge. Exposed part of the coxosternite ca. 1.8 times as wide as long; anterior margin slightly projecting forward, without denticles but with a medial shallow concavity; coxopleural sutures complete, entirely ventral, sinuous, and diverging forward; chitin-lines incomplete, pointing lateral to the condyles. Basal distance between the forcipules ca. 0.2 of the maximum width of the coxosternite. Forcipular trochanteroprefemur approximately as long as wide and intermediate articles distinct, without denticles. Tarsungulum ca. 3.0 times as long as wide, and 1.5 times as long as the trochanteroprefemur; both the external and the internal margins uniformly curved, but for a mesal moderate basal bulge bearing a subconic, stout denticle; ungulum not flattened. Poison calyx elongate, ca. 2 times as long as wide, in the forcipular intermediate articles.

Leg-bearing segments. A total of 53 pairs of legs. Metatergite 1 slightly wider than the subsequent one, without pretergite. No paratergites. Metasternites about as long as wide in the anterior part of trunk, whereas up to 1.5 times as long as wide in the posterior part. No obvious “carpophagus ” pits. Glandular pores arranged into a sub-elliptical transverse field on the posterior part of each metasternite, from the first to the penultimate leg-bearing segments, but separated into two paired fields between leg-bearing segment 19 and 50. The entire pore fields on the anterior part of the trunk are ca. 3 times as wide as long, with the anterior margin slightly concave, those on the most posterior segments are ca. 1.5 times as wide as long. Legs of the first pair slightly smaller than the subsequent ones, which are slightly longer than the width of the trunk. Leg claws simple, uniformly bent; a pair of accessory spines, the anterior one reaching ca. 30–40% of the length of the claw, the posterior one much shorter.

Ultimate leg-bearing segment. Pleuropretergite without sulci separating pleurites. Metatergite subtrapezoid, ca. 1.3 times as wide as long, lateral margins convex and converging backward, posterior margin medially truncate. Metasternite subtrapezoid, about as long as wide, forward ca. 1.9 times as wide as backward, lateral margins slightly concave and converging backwards; setae denser close to the posterior margin. Coxopleuron ca. 1.8 times as long of the metasternite; setae denser close to the postero-mesal and posterior margin. Coxal organs of each coxopleuron opening through ca. 25 independent pores, scattered on the ventral (13 on the right, 16 on the left), lateral (6 on the right, 5 on the left) and dorsal (4 on the right, 5 on the left) sides; the largest pores ca. 45–50 μm wide. Telopodite ca. 9–10 times as long as wide, ca. 1.3 times as long and ca. 1.3 times as wide as the penultimate telopodite; 6 articles, all similar in width, the tarsus 2 ca. 1.4 as long as wide and ca. 0.5 as long as the tarsus 1; lateral and ventral side with dense setae mostly less than 50 μm long. Pretarsus claw-like, distinctly shorter than the claws of the preceding legs, apparently without accessory spines.

Postpedal segments. Genital sternite separated by oblique sulci from pleurites. Gonopods elongate, apparently uniarticulate, separated at the basis, with penis in between. Anal organs apparently lacking.

Figures

Fig.3 Plutogeophilus jurupariquibaba gen.n. sp.n.: a anterior part of body, dorsal view; b–c head and forcipular segment, dorsal and ventral views, respectively; d–e posterior part of body, dorsal and ventral views, respectively. Photos: ♂, ISLA 11879, holotype. Scale bars: 0.4 µm