Pandirodesmus zogbiae, Romero-Rincon & Bouzan & Ferreira, 2025

Romero-Rincon, Juan, Bouzan, Rodrigo S. & Ferreira, Rodrigo L., 2025, The first troglobitic species of the extraordinary genus Pandirodesmus Silvestri, 1932 from the Brazilian Amazon (Polydesmida, Chelodesmidae, Pandirodesmini), Zootaxa 5673 (4), pp. 571-584 : 575-581

Pandirodesmus zogbiae sp. nov.

urn:lsid:zoobank.org:pub:CF68904F-6E05-4A12-A463-25FE3829DCCF

Figs 1–8

Diagnosis. The new species differs from congeners by the following combination of characters: Inconspicuous heteropody ( Figs 1D , 2 ), slightly more evident on the first pairs of legs; presence of claws on all legs ( Fig. 5A ); gonopods particularly similar to those of P. jaggernauthi by a primary branch longer, strongly curved and hookshaped, but with prefemoral process elongated, broad and with a subtruncated apex, and a secondary branch small, broad and with a basolateral fold inflexed ventrally ( Figs 6 , 7 ). See also the key below.

Etymology. The specific epithet honors the speleologist Leda Zogbi, whose exceptional dedication to the study, exploration, and mapping of Brazilian caves has greatly advanced speleological knowledge in the country. Her contributions have been instrumental in supporting and improving cave conservation strategies in Brazil. The epithet is Latinized and used as an adjective, in tribute to her remarkable achievements.

Material examined.

Holotype. BRAZIL ● ♂; Pará, municipality of Aveiro, Paraíso Cave , (-4.0752, -55.4587), 60 m a.s.l.; 5 October 2020. Ferreira, R. & Souza, M. leg. (ISLA-125959).

Paratypes. ● 1♂; same data as holotype, (ISLA-125961) ; ● 1♂; same data as holotype, (ISLA-125964) ; ● 1♂; same data as holotype, (ISLA-125965) ; ● 1♀; same data as holotype, (ISLA-125966) ; ● 2♂, 1♀; same data as holotype, (ISLA-125967) ; ● 4♂, 6♀; same data as holotype, (ISLA-125968) .

Description.

Measurements. Head + 20 rings (including telson), males ca. 12.5 mm in length and 1.15 mm in width on midbody rings. All body surfaces show sediment adhesion, but in lesser proportions on prozonites, antennae, sternites and gonopods ( Figs 1D , 2 ).

Color. In life (with sediment adhesion) deep orange 51 to light yellow 86; from highest to lowest sediment adhesion, respectively. When preserved clean and in 75% ethanol, white 263 to pale yellow 89.

Head. Head rough except for clypeus, facial setae moderate and translucent, number difficult to assess. Epicranium with two small dorsal knob-like structures and, below them, with 2+2 long setae on vertex ( Fig. 3A ). Labrum with three smoothly rounded teeth and a single row of 14–16 moderate labral setae ( Fig. 3A ). Clypeus with two irregular rows of setae, one supra-labral with 7–8 setae, 3 or 4 on each side, and above this a row of long setae, three on each side ( Fig. 3A ). Antennae long, slightly clavate, densely setose ( Fig. 3A, B ), in situ almost reaching the end of ring 2; in length, antennomere 2>3>5>4>6>1>7, antennomere 4 with some long setae on knobs. Terminal antennomere (disc) with four long and evident sensory cones located together inside a membranous area. Gnathochilarium as usual for a Polydesmida ( Fig. 3B ); mentum with a longitudinal row of three short setae, each lamella lingualis with four strong and short setae in a longitudinal row and two long setae on distal part, stipes with ~5 long setae in distal part and ~5 short setae irregularly positioned; cardo small, kidney-shaped. Inner and outer stipital palps each with a group of rod-shaped sensilla at tip ( Fig. 3D ).

Trunk. Collum short, narrow, inconspicuous, on each side with six closely spaced protuberances, each protuberance with a long seta ( Fig. 3E ). Second ring with a lateral spine-shaped projection in anterior part like a pleural keel extended. Body rings with conspicuous projections dorsolaterally formed by individual protuberances at their tips, each with a seta: projections on ring 2 formed by two protuberances, ring 3 by three protuberances, ring 4 by four protuberances, rings 5 and 6 by 4–6 protuberances ( Fig. 3E ), rings 7–18 by 2–4 protuberances, ring 19 and 20 by one protuberance. From ring 7 on, the projections less conspicuous dorsally and in the middle of them with two groups of protuberances: anterior group usually with 2–4 larger and scattered protuberances and posterior group with 3 protuberances in a transverse row ( Figs 4C , 5C ); both groups separated by a transverse field of irregular excavated cells ( Fig. 4C ). Prozonite ( Figs 4C , 5C, 5D ): anterior part of prozonite with small, irregular, scale-shaped units, transverse ridge marked by a few suboval and excavated cells, separated from each other and surrounded by small, deformed irregular units of anterior part. Posterior part of prozonite with two transverse rows, each with subrectangular cells of unequal size (second row with smaller cells) and closer together than transverse ridge. Pore formula almost normal: 5, 7, 9, 10, 12, 13, 15–18, ozopores opening laterobasally on projections ( Fig. 4D ). Sterna moderately setose, with a densely setose tubular projection on each side of coxa in the first rings ( Fig. 3A ) and a pair of traceable sternal cones on rings 5 and 6 (male), each cone with a strong and long seta ( Fig. 4A ). Epiproct short, subtriangular, extending past distal paraproctal margins, with four subapical rows, each-giving rise to a long seta. Anal valves smooth, with two strong setae on each valve. Hypoproct small, semi-lunar, with two protuberances supporting one long seta each. Legs very long and slender, only slightly longer (anterior pair) or shorter (posterior pair) alternating on the first rings. Starting with leg 3, each leg with tubular spiracles arising dorsally above coxae ( Fig. 4B ). Midbody podomeres normal, but moderately long and slender; in length: femur> tibia ≥ tarsus> postfemur> prefemur> coxa. Claws present on all rings, even in the first three pairs, narrow, fine, and difficult to distinguish among the surrounding long and filiform setae, these being only slightly larger and wider than claws ( Fig. 5A ). All podomeres covered with numerous long setae, unmodified, neither ramose nor dendriform like its congeners ( Fig. 5B ).

Gonopods. Gonopod aperture oval and minute, laterobasal margins of aperture extended ventrally. Gonopods in situ ( Fig. 4A ) held parallel to each other, telopodites fully exposed. Coxae (cx) small, closely appressed together, each cx with two dorsal macrosetae and a prominent coxal process laterodorsally (see arrows; Figs 6C , 7B, 7C ). Cannula (ca) originating at cx apex, directed posteriorly before sharply bending towards prefemoral region (pfe), pfe densely setose, as usual. Telopodite comprising three large branches: a prefemoral process (pfp, in blue), a secondary branch (sb, in green; = acropodite process), and a primary branch (pb, in yellow; = solenomere) ( Fig. 6 ). pb a hook-like structure, being the longest branch, carrying the prostatic groove; distal portion uniramous and supporting the solenomere (sl). sb the smallest and least conspicuous, located between pfp and pb, broad and with a ventrally folded basolateral fold. pfp irregular, elongated and broad, with a subtruncated apex and somewhat elongated vertices, slightly constricted mesally at about midway.

Habitat and threats. Pandirodesmus zogbiae sp. nov. has been recorded exclusively from Paraíso Cave. Despite targeted sampling in several nearby caves, no individuals have been found outside this system. It is worth noting that the limestone formation associated with Paraíso Cave is geographically limited in extent, whereas most of the surrounding caves are developed in sandstone. As these sandstone caves appear to have low subterranean connectivity with Paraíso Cave, the apparent narrow endemism of this species could be accounted for.

Within Paraíso Cave, P. zogbiae sp. nov. has only been recorded in the eastern part of the cave ( Fig. 1A ), where it has been found in just two of the surveyed transects. However, individuals have also been encountered occasionally in other parts of this same sector, always walking on muddy substrates ( Fig. 1C, D ), particularly near streams that flow through major conduits in this portion of the cave. The species has never been observed on other substrate types, such as cobbles, speleothems, or bat guano, nor in the western portion of the cave, which is characterized by extensive accumulations of guano deposited by huge bat colonies. This area, considered a highly eutrophic “bat cave” also harbors abundant scavenging troglophilic invertebrates, especially cockroaches ( Blaberus spp. ), which may competitively exclude P. zogbiae sp. nov. or make the habitat unsuitable. Although decaying wood and fragmented plant debris are the predominant organic materials present in the habitat, only mineral sediment has been observed in the digestive tract of the specimens ( Fig. 3F ), suggesting a possible specialization in deposit feeding or sediment filtering.

Interestingly, although the new species is completely unpigmented (an expected trait for a troglobitic species), live individuals have been consistently observed coated in clay ( Fig. 1D ). It seems important to emphasize that this biological survey represents a single sampling event, and many cave areas remain unexplored. Therefore, our current understanding reflects a minimum estimate of the species’ distribution ( Fig. 1A ).

Although the immediate surroundings of Paraíso Cave remain relatively well preserved, much of the mapped cave system (when projected onto the surface) is located beneath a forest fragment of the Amazon. This remnant is increasingly isolated, as it is encircled by deforested areas resulting from expanding logging activities and the conversion of land to pasture, particularly near the Trans-Amazonian highway. Some areas adjacent to the cave have already undergone severe environmental degradation. For example, one of the main surface streams feeding the cave (part of an interconnected network of subterranean watercourses) flows through a deforested zone before infiltrating the limestone substrate. These surface streams are crucial for transporting organic material, especially decomposing plant matter, into the cave ecosystem.

Deforestation in the cave’s vicinity therefore poses serious threats to its ecological integrity. It may reduce the input of organic matter and increase sedimentation, both of which can degrade habitat quality within the cave.Siltation and the loss of substrate heterogeneity are particularly concerning, as they diminish the diversity of microhabitats that support the rich invertebrate fauna. Given that substrate variability is closely linked to invertebrate diversity in subterranean systems, such alterations could have profound impacts on the cave’s biological communities.

Notably, Paraíso Cave has already revealed an impressive biological richness. A single expedition uncovered at least 10 cave-restricted species, although most still remain undescribed. One exception is the scleropactid isopod, Circoniscus paradisus , recently described by Galo et al. (2025). A particularly noteworthy aspect of this cave lies in its remarkable diversity of cave-restricted millipedes. Over half of the troglobitic species identified during the expedition belong to this group, highlighting the cave’s significance as a potential hotspot of diplopod diversification in subterranean environments. This highlights the urgent need for continued taxonomic work and additional surveys, as further sampling is likely to uncover even more troglobitic species. Such discoveries are consistent with patterns seen in other subterranean biodiversity hotspots, which often emerge after multiple, focused collection efforts.

Given its biogeographic isolation, long-term environmental stability, and geological history shaped by significant past climatic fluctuations, Paraíso Cave holds a strong potential to be recognized as a major hotspot of subterranean biodiversity in the Amazon region in the future.

Figures

FIGURE 1. A. Map of Paraíso Cave detailing the distribution area of Pandirodesmus zogbiae sp. nov. B. Cave entrance. C. Conduit where the specimens were found and collected. D. Living male. Red stars indicate the general collection points during the field phase, while the area delimited by the red line indicates the presumed distribution area of the new species.

FIGURE 2. Habitus of Pandirodesmus zogbiae sp. nov. (A, holotype, ISLA-125959; B, paratype, ISLA-125965). A. Clean male. B. Male with adhering sediment. Scale bar: 1 mm.

FIGURE 3. Pandirodesmus zogbiae sp. nov. (A, paratype, ISLA-125964; B-F, paratype, ISLA-125961). A. Head, ventral view. B. Right antenna. C. Gnathochilarium D. Detail of palps from gnathochilarium. E. Anterior part of the body, dorsal view. F. Stomach contents. Scale bars: A, E = 0.5 mm; B, F = 0.1 mm; C = 0.25 mm; D = 0.05 mm.

FIGURE 4. Pandirodesmus zogbiae sp. nov. (paratype, ISLA-125961). A. Middle part of the body, ventral view. B. Spiracules. C. Detail of prozonite and metazonite of the middle part of the body, dorsal view. D. Detail of ozopore. Scale bars: A–C = 0.25 mm; D = 0.025 mm.

FIGURE 5. Pandirodesmus zogbiae sp. nov. (paratype, ISLA-125961). A. Leg of the middle part of the body. B. Detail of setae of femur. C. Telson, dorsal view. D. Detail of prozonite. Scale bars: A, C = 0.25 mm; B = 0.025 mm; D = 0.1 mm.

FIGURE 6. Pandirodesmus zogbiae sp. nov. (A, paratype, ISLA-125961; B-D, paratype, ISLA-125964). A. Gonopods in situ, ventral view. B. Right gonopod, dorsomesal view. C. Left gonopod, mesal view. D. Detail of apical part of left gonopod, mesal view. Arrow represents coxal apophysis. Abbreviations: ca: cannula, cx: coxa, pb: primary branch, pfe: prefemoral region, pfp: prefemoral process, sl: solenomere, sb: secondary branch. Scale bars: A = 0.4 mm; B, C = 0.2 mm; D = 0.05 mm.

FIGURE 7. Left gonopod of Pandirodesmus zogbiae sp. nov. (paratype, ISLA-125964). A. Mesal view. B. Lateral view. C. Posteromesal view. D. Ventral view. Arrows represent the coxal apophysis. Abbreviations: ca: cannula, cx: coxa, pb: primary branch, pfe: prefemoral region, pfp: prefemoral process, sl: solenomere, sb: secondary branch. Scale bars: A–C = 0.2 mm; D = 0.1 mm.

FIGURE 8. Distribution map of the genus Pandirodesmus Silvestri, 1932.