Chonodesmus simplex, Reyes-Peñata & Romero-Rincon & Martínez-Torres & García-Sarmiento, 2025

Reyes-Peñata, Liseth Alejandra, Romero-Rincon, Juan, Martínez-Torres, Daniela & García-Sarmiento, Martha J., 2025, Two new species of the flat-backed millipede genus Chonodesmus Cook, 1896 (Polydesmida, Cryptodesmidae, Cryptodesmini) from Colombia with a redescription of the type species, Zootaxa 5659 (2), pp. 223-239 : 233-237

Chonodesmus simplex new species

Figs 7–9

urn:lsid:zoobank.org:act:C287B264-CC5F-4506-88ED-DF5A32EEF329

Diagnosis. The new species differs from congeners by reduced branches on the apical processes of telopodite, especially on the posterior apical process. Differs from C. alatus , C. chicaque sp. nov. and C. gervaisi , by a single short apical process on the posterior lamellar process. Solenomere with two tooth-like projections in medial region, absent in C. muisca sp. n.

Etymology. A Latin adjective referring to the particularly simple telopod of the gonopod.

Material examined

Holotype. COLOMBIA ● ♂; Risaralda, Parque Regional Natural Ucumarí, La Pastora (4.711851, -75.485392); 2540 m a.s.l.; under bark of fallen log; daytime hand collection; 15 Jan. 2025. J. Romero-Rincon & D. Millán- Sainea leg.; MHN-UPN-MD-437.

Paratypes. ● 1 ♀; same data as holotype; MHN-UPN-MD-438 .

Description

Measurements. Head + 20 rings (including telson), male 15.5 mm long and 3.5 mm wide; female 14.5 mm long and 3.0 mm wide.

Color. Head with epicranium dark reddish brown 44. Fronts and apical border of clypeus moderate reddish brown 43, central region of clypeus pale orange yellow 73, labrum transparent. Collum with central region dark reddish brown 44 with apical and distal area pale orange yellow 73. Prozonites and metatergites dark reddish brown 44, last 6 rings greenish black 157. Paranota with central area greyish reddish orange 39 with distal region pale orange yellow 73 and anterior edges transparent. Sternites moderate reddish brown 43, legs pinkish white 9. Antennae: antennomeres 1 pale orange yellow 73, 2–3 light greyish reddish brown 45,4–6 dark greyish reddish brown 47, 7–8 white, sensory cones darker than the others.

Head. Head convex, strongly inclined downward and typically covered by collum. Clypeolabral region with very short setae. Epicranial suture not distinguishable. Antennae short, reaching posterior part of second body ring when extended backward, stout and claviform; antennomeres V, VI with a compact group of sensilla ( Fig. 8A ). Collum about twice as long as head, but differs from its congeners by an arched anterior outline and a subrectal posterior outline. Posterior edge about as long as the first prozonite. Its surface covered with a series of faint but indistinguishable and sparse tubercles, each with a small seta visible only under UV light. Relative length of antennomeres: 5>6>4>2>3>1≥7 ( Fig. 8A ).

Trunk. Prozonites short, slender and glabrous. Metazonites broad, metatergites densely hairy and tuberculate, with four rows of tubercles extending transversely to bases of paranota, each tubercle with a conspicuous, long and slender seta; setae being equal in length. Paranota broad with lobed distal and basal margins, anterior margin straight and terminating in a setiform tooth-shaped projection, lateral margin with 3 or 4 subtriangular setigerous divisions, each with a long macroseta located at the posterolateral corner and another of similar length at the inner base ( Fig. 8D ). Posterior margin with 6 or 7 distinct marginal areas. Ozopore opening flush on surface in distal part of second area; ozopore formula normal. On posterior rings, paranota showing caudal projection, these being more pronounced closer to telson. Axial line absent. Sternites of equal size lengthwise and widthwise. Between coxae 6 with a pair of small, elongated, and setose protuberances. Coxae 7 noticeably wider apart than others. Legs long and slender. Prefemora 7 in males with a small and rounded spine ( Fig. 8E ). Leaf blade with serrated and acuminate appearance. Epiproct subtrapezoidal, with a straight and slightly elongated basal area, without lobes. Medial area with lobed and convex margins, distal area straight. Setae dense, uniform, long and slender. Margin setae irregular in arrangement and length ( Fig. 8F ).

Gonopods. Gonopod ( Fig. 9 ) aperture subovoid with medial part of anterior margin elongate distally and excavated, posterior margin slender and slightly elevated. Cx prominent and without setae, ventral surface of Cx with a median commissure connecting both Cx; ca tubular and normal structure. Pfe slightly reduced, and densely setose as usual, similar to that observed in other congeners. Telopodite robust, with simple apical process. Lamellar process fused, although with a faint differentiation between its anterior and posterior regions. A branch slightly curved to anterior region. S short and acuminate with presence of two teeth on medial region directed mesoventrally and with a group of setae in the inner basal region. hm adjacent to S with an irregular edge; base of hm densely setose. Lateral surface of telopodite with a densely pilose pad. Seminal groove in basal part of telopodite difficult to observe because of its location behind median commissure in Cx ventral part.

Female. Non-sexual characters as in males, except for lesser dark and uniform coloration, more robust body, lacks the modification of the sternite 7 and spine on prefemora 7.

Distribution. Only known from La Pastora, Parque Regional Natural Ucumarí, Pereira, Risaralda Department, Colombia, 2540 m a.s.l. ( Fig. 10 ).

Remarks. The conformation of the gonopod suggests an anterior and posterior lamellar processes fused, as there is no obvious separation between them. A branch of the anterior lamellar process is absent and the posterior lamellar process has a distinguishable branch (vs. all congeners; presence of three or more processes of different lengths).

Figures

FIGURE 7. Chonodesmus simplex n. sp, male holotype (MHN-UPN-MD-437). A. Habitus in dorsal view. B. Habitus in ventral view. Scale bar: 2 mm.

FIGURE 8. Chonodesmus simplex sp. nov., male holotype (MHN-UPN-MD-437). A. Antenna, posterior view. B. Anterior part of collum, dorsal view. C. Aperture of gonopods, ventral view. D. Left paranotum of ring 10, dorsal view. E. Right leg 7, posterior view. F. Detail of telson, dorsal view. Scale bars: 0.2 mm.

FIGURE 9. Left gonopod of Chonodesmus simplex sp. nov., male holotype (MHN-UPN-MD-437). A, D. Mesal view. B, E. Ventral view. C, F. Lateral view. Abbreviations: ca: cannula, Cx: gonocoxae, hm: hyaline membrane, Pfe: prefemoral region, S: solenomere. Scale bar: 0.5 mm.

FIGURE 10. Distribution map of Chonodesmus Cook, 1896.