Cylindroiulus villumi , Reboleira, Ana Sofia P. S. & Enghoff, Henrik, 2018

Reboleira, Ana Sofia P. S. & Enghoff, Henrik, 2018, First continental troglobiont Cylindroiulus millipede (Diplopoda, Julida, Julidae), ZooKeys 795, pp. 93-103: 94-98

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Cylindroiulus villumi

sp. n.

Cylindroiulus villumi  sp. n. Figs 1, 2, 3, 4, 5

Type material.

Holotype, male, Portugal, Estremenho karst massif, Algar do Pena Cave (Coordinates: 39°27'54.40"N, 8°48'25.24"W), ASPS Reboleira leg., 04 Nov 2014. Paratypes: Portugal, Estremenho karst massif, Algar do Pena Cave, ASPS Reboleira leg., 04 Nov 2014, 1 male, 2 females, 4 juvenile males and 1 juvenile; same data but 28 Mar 2018, 1 female and 1 juvenile.


A medium to small, blind, and unpigmented species of the Cylindroiulus perforatus  -group. Anterior constriction pronounced and pilosity of the telson scarce. Differs from all other species in the group by the lack of eyes and by the shape of the gonopod mesomerite which is shorter than the promerite (>< C. fenestratus  Read, 1989, C. perforatus  Verhoeff, 1905, and C. ventanaea  Read, 2007) and apically rounded (>< C. anglilectus  Read, 2007). Further differs from other group members except C. anglilectus  by the much shorter paracoxal process.


Male holotype: 37 podous + 1 apodous rings + telson; females up to 41 podous + 1 apodous rings + telson.

Body length up to 13 mm in females and 11.4 mm in males. Vertical body diameter (H): 0.9 mm (females) and 0.7 mm (males). Integument unpigmented (Figure 1); eyes absent (Figs 1, 2A, B). Length of antennae 0.8 mm (Figure 2B), with sensory cones elongated and with a fine longitudinal striation (Figure 2C, D) ending in a pore as shown in Figure 2E. Anterior constriction of body pronounced in dorsal view. Limbus of the the normal type sensu Enghoff (1982), i.e., with simple marginal cells without denticles on the free margin. Length of legs (Figure 3A) 1.8 mm, tarsus being the longest podomere. Length of claw 9.6% of total leg length. Accessory claw exceptionally short: 92% shorter than the claw (Figure 3B). Preanal ring with a very short blunt projection, almost glabrous, only with 5 lateral setae (Figure 3C, D), subanal scale with two setae, anal valves with two long ventral setae on the lateral part of the posterior margin, rarely up to two additional setae were observed, however the number is variable and may even differ between right and left valve of the same specimen (Figure 3C). Male first pair of legs modified as typical of the genus, hook-like.

Gonopods  (Figure 4): Promerite in anterior view (Figure 4D), higher than mesomerite (Figure 4D, E), with rugose area facing apical part of the mesomerite (Figure 4E). Mesomerite (Figure 4E): slender, shorter than, and fitting into, apical concavity of promerite. Paracoxal rim moderately developed. Paracoxal process not very prominent, rather short and mostly fused to solenomerite (Figure 4F). Solenomerite as in Figure 4A, B, C, F; very simple, subrectangular in lateral view, with denticles on anterior flagellum-conducting lamella (Figure 4C).

Vulvae  (Figure 5 A–B): Vulvae  typical of the C. perforatus  -group: glabrous operculum, bursa with a few setae and the receptaculum seminis as a stalked sphere with a small tubular appendix.


The new species is dedicated to the VILLUM Foundation, named after Villum Kann Rasmussen (1909-1993), as recognition for the generous support to research in natural sciences.


Cylindroiulus villumi  sp. n. was discovered in the cave Algar do Pena, located in the Santo António plateau, the central sub-unit of the Estremenho karst massif in central Portugal. It was found inside a big piece of deadwood located at the base of the entrance pit to the cave, at a depth of 33 meters below the surface.


Algar do Pena is the largest underground chamber of Portugal. The temperature is very constant 13 ± 1 °C and relative humidity close to saturation. It is a very oligotrophic cave where only a few cave-adapted species are recorded: the spider Nesticus lusitanicus  Fage, 1931, the terrestrial isopod Trichoniscoides meridionalis  Vandel, 1946, the springtail Onychiurus confugiens  Gama, 1962; the dipluran Podocampa cf. fragiloides  Silvestri, 1932; and the beetle Trechus gamae  Reboleira & Serrano, 2009 ( Reboleira 2007, 2012, Reboleira and Ortuño 2011, Reboleira et al. 2009, 2010, 2011). The holotype and a juvenile male paratype have ' Amphoromorpha  ' fungi on the head and antenna, similar to those observed by Enghoff and Reboleira (2017) on other millipedes.