Xanthotropis media Almeida & Shelley & Rafael 2018, new combination

Xanthotropis media (Golovatch, Hoffman & Spelda, 2004), new combination

(Figs. 1, 3A–D, 4A–D)

Haematotropis media GoloVatch, Hoffman, Spelda, Vohland & SeitZ, 2004: 63, figs. 31–38, 58; Pena-Barbosa, 2018 (online catalog).

Type specimen. Male holotype (Instituto Nacional de Pesquisas da Amazônia, INPA), collected by W. Hanagarth on an unspecified date in July 1999 near EMBRAPA-CPAA along highway A-010, 29 km N junction with highway 174, Amazonas, Brazil. The vial label reads "1SP 1031199–2, Brasillien: Amazonas, Manaus, Embrapa-CPAA, km 29 der AM-010 Weg Manaus-Itacoatiara, Respirations-messungen, Diplopoda Nr. 27" / "Myriapoda—Diplopoda—Aphelidesmidae, Haematotropis media Golovatch, Hoffman & Spelda, 2004, INPA 352, Holótipo".

Diagnosis. With the characters of the genus.

Preserved coloration. Unknown after 18 years in preservative. Epicranium, interantennal region, genae, and frons dark brown, fading into light yellowish pigmentation peripherally on labrum, clypeus, and genal margins (Fig. 3A). Antennomeres yellow, thus contrasting with dark head (Figs. 3A–B). Metaterga brown, paranota yellow and becoming progressively lighter laterad; caudal margins with narrow yellow bands mediad becoming progressively thinner caudad, absent from caudal metaterga (Figs. 3B–D). Telson brown basally, yellow apically (Fig. 3D). Distal podomeres light yellow (Fig. 3B).

Holotype. Length 34.0 mm, maximum width 4.3 mm; W/L ratio 12.6%. Head (Figs. 3A–B) generally smooth and shiny, coriaceous around subovoid incisura lateralis. Epicranial suture shallow, not anteriorly bifid. Interantennal isthmus narrow, 0.4 mm. Antennae extending backwards to around midlength of 2nd metatergite. Antennal setae sparse except on subglobose 1 st antennomere, 2–5 clavate, 6 longer and cylindrical, 7th short and truncate, with four apical sensory cones arranged in diads, antennomere margin invaginated between latter. Antennomere lengths (1–7, in mm): 0.4, 0.9. 0.9, 0.9, 0.9, 0.8, 0.3. Facial setae as follows: epicranial and interantennal absent, frontal 2–2, clypeal 6–6, labral about 5–5, merging with clypeal series and continuing for short distances along genal margins. Trunk (Figs. 3B–D). Pro- and metaterga glabrous and glossy, former lightly coriaceous laterad, latter with inconspicuous microgranulations. Collum length (mm) 1.4, width 4.1; surface lightly coriaceous along anterior and caudal margins, with horizontal semilunar depression mediad, caudolateral margins sublinear, rounded anteriad, lightly coriaceous laterad (Fig. 3B). Paranota slanted ventrad (Figs. 3A–B); those of metaterga 2–4 with one anterolateral tooth, largest on 3rd paranota (Fig. 3C); caudolateral corners extending caudad beginning on 4th paranota, becoming longer and progressively more acuminate caudad. Peritremata slightly thickened, elevated above dorsal paranotal surfaces, with microgranulations on anterior and posterior margins; ozopores located caudal to midlengths on paranota 5, 7, 9, 10, 12, 13, 15–19, opening laterad. Sides of metazona smooth, generally without grooves or impressions. Pregonopodal sterna smooth and glabrous, those of rings 4, 5 with two pairs of rounded lobes, caudal margin of 6th sternum recessed to accommodate gonopodal apices when trunk compressed. Postgonopodal sterna smooth and glabrous, those of rings 8–18 with two pairs of short, rounded projections and inconspicuous bicruciform impressions. Legs generally narrow and glossy with microgranulations and short setae on all podomeres; 1 st and 2nd legs short and crassate, gonapophyses short and tubular; 3rd–7th legs longer, lengths subequal. Postgonopodal legs of subequal lengths and setal tufts on tarsi; tarsal claws short, curving gently apically. Telson subtriangular, narrowly truncate and sublinear apically (Fig. 3D); paraproctal margins strongly elevated with two setal pairs arranged vertically proximal to rims; hypoproct semilunar. Gonopodal aperture elliptical, approximately 1.3 mm wide and 0.9 mm long at midpoint; anterior margin slightly concave, sides elevating progressively caudad then lowering to flat caudal margin. In situ gonopodal configuration unknown; right gonopod missing and left dissected for present examination. Gonopod structure (Figs. 4A–D) as follows: Coxa without apophysis, with three ventral setae equivalent in lengths to basal ones on prefemur. Latter shorter than coxa (Fig. 4A), demarcated from acropodite by cingulum, densely covered by setae around origin of spermatic groove, setae extending short distance along acropodite (Figs. 4A; 4D). Acropodite (Fig. 4 C-D) elongated, curvilinear proximad, indented at midlength then expanding distad with prolonged ventral corner, with retrorse, apically rounded, dorsally lamellate projection arising from medial surface and curving gently dorsad to level of acropodital midlength, extending linearly from origin of dorsal lamella, apically emarginate. Solenomere long, narrow, and acicular, arising at level of cingulum and basally on acropodite, curving broadly laterad away from acropodital stem then sinusoidally along dorsal surface of its distal half, sides narrowing smoothly, apically acuminate and virtually invisible, terminating just beyond lateral acropodital margin at level of retrorse lamella (Figs. 4C–D). Spermatic groove arising in pit in prefemir, angling along medial surface of acropodite to base of solenomere, opening apically on latter (Fig. 4D). Total length of telopodite 2.4 mm. Width of femur in dorsal view 0.5 mm.

Distribution. Known only from the type locality, approximately 25 km north of Manaus, Amazonas, Brazil.

Remarks. The shades of pallid brown coloration reported by Golovatch et al. (2004) is the faded pigmentation after 18 years in preservative; we suspect that the varying shades were actually black to gray in life. Despite fading, the dorsal color pattern can still be discerned, and the millipede appears to be uniformly dark middorsally with narrow, lighter bands along the anterior and caudal metatergal margins (Fig. 3B) connecting with the broad and substantially lighter paranotal markings.

Haematotropis is defined by the small anterolateral teeth on paranota 2–4 and the elongated acropodital femur (Fig. 2C). That X. media n. comb. possesses such features explains the original assignment, but based on gonopodal similarities, the authors also suggested placement in Aphelidesmus. We conclude that its external features and the gonopodal configuration are sufficiently different from the patterns in both Haematotropis and Aphelidesmus that generic distinction is warranted and therefore establish Xanthotropis n. gen., which is presently monotypic.