Chonodesmus alatus ( Peters, 1865 )

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 : 225-228

Chonodesmus alatus ( Peters, 1865)

Figs 1 , 2 , 10

Polydesmus (Cryptodesmus) alatus Peters, 1865: 621 (original description, based on three specimens).

Cryptodesmus alatus : Attems, 1899: 266; Carl, 1914: 958, figs 246–247; Attems, 1940: 212, fig. 297.

Chonodesmus alatus : Cook, 1896: 23; Cook, 1911: 468, figs 7–10 (with the first line drawings of some morphological structures); Carl, 1914 (with the first illustration of the gonopods of C. alatus ); Moritz & Fischer, 1978: 132 (information on type material of three specimens, mistakenly referred to as one male and two females syntypes of Polydesmus (Cryptodesmus) alatus (ZMB 305)); Moritz & Fischer, 1978: 136 (erroneous information referring to a female from the type series of Polydesmus (Cryptodesmus) alatus as holotype of Stictodesmus creper (ZMB 13169)); Moritz & Fischer, 1978: 147 (erroneous information referring to another female from type series of Polydesmus (Cryptodesmus) alatus as type of Chonodesmus regularis ).

Diagnosis. Based on gonopodal characteristics, this species appears to be particularly similar to C. muisca sp. nov., but it differs from congeners by the presence of two branches on the posterior lamellar process: first branch elongate and falcate, directed laterally, vs the second branch about half the length of the first.

Material examined

Lectotype (designated herein). COLOMBIA ● ♂; Bogotá, D.C. ; (4.609791, -74.081744); 2582 m a.s.l.; dry and pinned; Linding leg.; ( ZMB-305 ).

Additional material examined. ● ♂; Tena , Cundinamarca (Tambo); (4.654936, -74.389989); 1343 m a.s.l; dry and pinned; Fuhrmann leg.; ( MHNG-ARTO-28917 ) .

Redescription

Measurements. Head + 20 rings (including telson), male 11.4 mm long and 3.3 mm wide.

Color. The original description stated that the whole animal was violet-red. Based on the preserved condition of the lectotype, head with epicranium, frons, and labrum grayish yellow 90. Collum dark orange yellow 72. Prozonites deep yellowish brown 75 on anterior rings, turning dark grayish red 20 towards posterior end; metatergites light olive brown 94 anteriorly, turning deep red 13 posteriorly. Paranota with central area dark orange yellow 72, becoming slightly lighter distally. Sternites moderate orange yellow 71, legs pale greenish yellow 104. Antennae: antennomeres 1–6 dark grayish red 20, 7–8 yellowish gray 92.

Head. Head convex, strongly inclined downward and dorsally covered by the collum, slightly setose. Clypeolabral region with very short setae. Epicranial suture indistinguishable. Antennae short, reaching posterior part of second body ring when extended backward, stout and claviform. Collum about twice as long as the head, with an arched anterior outline typical of the group ( Fig. 1D ), although with the posterior margin straight, differing from that of congeners; posterior edge is about as long as the first prozonite. Its surface covered by a series of tubercles arranged in six transverse lines, anterior zone with a row of lobes varying between 20 and 21. Relative length of antennomeres: 6>5>2>4>3>1>7.

Trunk. Prozonites short, slender and glabrous, widening slightly towards caudal region. Metazonites broad, metatergites densely setose and tuberculate, with three rows of tubercles extending transversely to the bases of paranota; each tubercle with a long slender seta; setae being equal in length. Paranota broad with lobed distal and basal margins, anterior margin straight and terminating in a dentiform setigerous projection, lateral margin with 3 or 4 subtriangular setose divisions ( Fig. 1F ). Posterior margin with 6 or 7 distinct marginal areas. Ozopores opening flush on surface between 2nd and 3rd area; ozopore formula normal. On posterior rings, paranota showing caudal projections, these being more pronounced closer to telson. Axial line absent. Sternites slightly wider between posterior pair of legs compared to anterior pairs. Coxae 7 notably wider apart than others and excavate. Legs long and slender. Epiproct subtrapezoidal, with a short basal area.

Gonopods. Based on illustration by Carl (1914: figs 246–247) ( Figs 1H , 2C–F ) aperture subovoid, with posterior margin slender and slightly elevated. Cx prominent and without setae, ventral surface of Cx with median commissure connecting both Cx; ca tubular and of normal structure. Pfe densely setose as usual, similar to that observed in other congeners. Telopodite robust and highly complex with apical processes typical of the genus. Posterior lamellar process with two branches arranged from left to right in ventral view for left gonopod: (1) falcate, oriented laterad, and (2) acuminate ca 1/2 the length of the first. Anterior lamellar process with a laterally curved branch, increasingly tapering towards apex. S short and slender with two teeth in medial region, hm with a serrate margin, extending over medio-anterior region of telopodite. Lateral surface of telopodite with a densely pilose pad. Seminal groove in basal part of telopodite difficult to observe because of its location behind medial commissure in Cx ventral part.

Distribution. Known from Bogotá, D.C. and Tena, Cundinamarca Department, Colombia, 1343–2582 m a.s.l. ( Fig. 10 ).

Remarks. The species C. alatus was described based on three individuals without information concerning their sex. Cook (1896) separated one of those specimens as the holotype of C. regularis (currently Cryptodesmidae ) and another one as holotype of Stictodesmus creper Cook, 1896 (currently Pyrgodesmidae ), without information on the sex of those specimens either. Carl (1914), provided the first illustration of the gonopods of C. alatus . Moritz & Fischer (1978) mistakenly referred to one male and two females as the syntypes of C. alatus , but actually a juvenile male had been designated as the holotype of C. regularis and the female as the type of S. creper . The type series, revised here, contains in fact the male lectotype of C. alatus , a juvenile male with gonopodal primordia that is the type of C. regularis , and the other female the type of S. creper .

Figures

FIGURE 1. Chonodesmus alatus (Peters, 1865) male lectotype (ZMB-305). A. Habitus in dorsal view. B, G. Habitus and labels. C. Anterior part of the body in ventral view. D. Detail of collum in dorsal view. E. Gonopods in ventral view. F. Detail of left paranotum of ring 9 in dorsal view. H. Drawings of gonopods by Carl (1914). Scale bars: A= 1 mm; C–D, E= 0.25 mm, F= 0.5 mm.

FIGURE 2. Chonodesmus alatus (Peters, 1865) (MHNG-ARTO-28917). A. Habitus in dorsal view. B. Habitus in ventral view. C, E. Left gonopod in mesal view. D, F. Left gonopod in lateral view. G. Labels. Abbreviations: ca: cannula, Cx: gonocoxae, hm: hyaline membrane, Pfe: prefemoral region, S: solenomere. Scale bar: 0.25 mm.

FIGURE 10. Distribution map of Chonodesmus Cook, 1896.