Bryodelphax arenosus Gąsiorek 2018, new species
Creators: name: Gąsiorek, Piotr
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Tardigrada
Heterotardigrada
Echiniscoidea
Echiniscidae
Bryodelphax
Bryodelphax arenosus

description: Bryodelphax arenosus new species
(Figs. 2–4, Tables 2, 3)
Material examined. All individuals were mature females. Holotype (slide no. MY.813.01) and 14 paratypes (slides MY.813.01–11), six additional processed for DNA extraction and sequencing. Type locality: Bako Peninsula, lowland coastal rainforest close to the Tajor Waterfall (1°43′24″N, 110°27′50″E; 106 m asl), moss from a tree, coll. Piotr Gąsiorek & Artur Oczkowski, 5 th August 2017. Holotype and nine paratypes deposited in the Institute of Zoology and Biomedical Research, Jagiellonian University, Kraków, Poland (slides MY.813.01–06), three paratypes deposited in the Natural History Museum of Denmark, Copenhagen (slides MY.813.07–09), and last two paratypes deposited in the Raffles Museum of Biodiversity Research, National University of Singapore (slides MY.813.10–11).
Description of the new species. Adults (i.e., from the third instar onwards, with developed gonopore; measurements in Table 2).
Body yellowish, pearly opalescent; eyes absent or not visible after preparation. Both primary and secondary clavae oval and small (Figs. 2, 3C, 4A). Cirri interni and externi with poorly developed cirrophores. Cirri A long (on average reaching ⅓ of the body length, whereas Bryodelphax typically has cirrus A /body length ratio around ¼; Figs. 2, 3A). Dorsal plates with faint intra-cuticular pillars visible only under 100× magnification with immersion oil (Figs. 3C, 4), better visible on the scapular and caudal plates (Figs. 3C, 4A, C), pillars on the posterior portion of the caudal plate are also the largest (Figs. 3C, 4C). Distinct dark ridges are present on lateral portions of the scapular, paired, and caudal plates, forming characteristic and stable ornamented pattern (Figs. 3B, C, 4). Pseudopores or pores (SEM observations are needed to verify the morphology of the cuticular depressions) minute and barely visible (visible in PCM as bright dots with blurred margins; Figs. 3C, 4), sometimes absent. Pseudopores/pores distributed unevenly, i.e., on the anterocentral portion of the scapular plate 8–21 pseudopores/pores per 100 μm 2 were observed (x =17, N=10; Fig. 4A), on the central portion of the caudal plate: 11–18 pseudopores/pores per 100 μm 2 (x =15, N=10; Fig. 4C), whereas sparse and bleak pseudopores/pores occur rarely on other, especially paired, plates. Scapular plate deeply faceted by dark ridges, with six or eight lighter rectangular areas in the central portion (Figs. 3A, C, 4A). Scapular sutures clearly separate lateral portions from the central part, extending from the base of cirrophore A to the posterior margin of the plate (Figs. 3B, C, 4A). Paired plates divided into two roughly equal anterior and posterior parts by a transverse stripe (Figs. 3, 4B). Caudal plate mildly faceted in the central part by the same dark ridges as the scapular plate (Fig. 3A), but the faceting is fainter and often poorly visible (Figs. 3C, 4C). Median plates 1 and 2 divided transversally into two unequal parts (Figs. 2, 3), and additionally the anterior portion of median 2 has a transverse suture (Fig. 3). Median plate 3 large, triangular in shape, and with a roundish posterior edge (Figs. 2, 3). Thin, non-sculptured supplementary lateral platelets present at the levels of median plates (three pairs of platelets on each body side: a pair between scapular plate and first pair of the segmental plates, a pair between paired plates, and a pair between second pair of segmental plates and caudal plate; Fig. 3B, C). Ventral cuticle smooth, without plates or intra-cuticular pillars. Papillae on legs I and IV absent or not detectable in PCM. Large, sclerotised pedal plates IV present, with irregular margin, but never forming a dentate collar (Fig. 3C, white arrowhead). External claws of all legs smooth, internal claws with minuscule bumps near their bases, which can be spurs (Fig. 3C, insert). However, they are not measurable in PCM since barely divergent from the claw branch.
No juveniles, larvae (i.e., the second and first instars, respectively) or eggs were found.
Remarks. All found specimens were mature females, thus it is likely that the new species is parthenogenetic.
DNA sequences. New 18S and 28S rRNA sequences were obtained for two specimens; each fragment was represented by a single haplotype and is deposited in GenBank: MH 414953 (18S rRNA, 1112 bp long), XX000000 (28S rRNA, 688 bp long). p-distances between sequenced species of Bryodelphax ranged from 0.8% to 2.8% (18S rRNA), and from 7.5% to 19.3% (28S rRNA) (Table 3).
Etymology. From Latin (h) arenosus = sandy, inhabiting sand. The new species was found in coastal lowland rainforest with peculiarly sandy soil (arenosols), atypical for this biome.
description: Published as part of Gąsiorek, Piotr, 2018, New Bryodelphax species (Heterotardigrada: Echiniscidae) from Western Borneo (Sarawak), with new molecular data for the genus, pp. 371-381 in Raffles Bulletin of Zoology 66 on pages 374-377, DOI: 10.5281/zenodo.5358943