Chaimowiczia tatus, Cardoso 1 & Bastos-Pereira 1 & Souza 2 & Ferreira 1, 2021

Cardoso 1, Giovanna Monticelli, Bastos-Pereira 1, Rafaela, Souza 2, Leila Aparecida & Ferreira 1, Rodrigo L., 2021, Chaimowiczia: a new Iuiuniscinae genus from Brazil (Oniscidea, Synocheta, Styloniscidae) with the description of two new troglobitic species, Subterranean Biology 39, pp. 45-62 : 45

Chaimowiczia tatus sp. nov. Figs 2 , 3 , 4 , 5

Material examined.

Holotype. • 1 Male; Bahia , Santana, Gruta do Padre cave, -13.216325°, -44.065194°, 11 July 2014, leg. R. L. Ferreira, ISLA 78105 . Paratypes. • 1 female, same data as for holotype, ISLA 78106; • 1 male 1 female, same locality as for holotype, 18 July 2019, ISLA 78107.

Diagnosis.

Chaimowiczia tatus sp. nov. is characterized by pereonite 1 epimera directed sideways; quadrangular antennal lobes; pleonites 3-5 epimera tips well developed, pleonite 5 short, not surpassing the apex of telson; and uropods endopod and exopod subequal in length.

Description.

Maximum length: male, 9 mm. Colorless, eyes absent (Figs 2A , 3A, B ). Dorsal surface smooth covered with scale setae with short triangular base and long sensory sheathed hair (Fig. 3C ). Cephalon (Fig. 3A, B ) frons with distinct suprantennal line, downward and truncate in middle, quadrangular antennal lobes. Body convex, pereonites 1-7 epimera quadrangular, widely separated and outwardly extended, pereonites postero-lateral corners progressively directed backward; pleon epimera 3-5 well developed (Fig. 2A ). Telson (Fig. 2B ) distal half subtriangular depressed with round apex. Antennula (Fig. 2C ) with three articles covered with thin setae, distal article longer than second article, with two apical aesthetascs. Antenna (Figs 2D , 3A ) surpasses pereonite 1 when extended backward, fifth article of peduncle as long as flagellum; flagellum with three articles. Right mandible (Fig. 2E ) with one penicil; left mandibles with two penicils (Fig. 2F ). Maxillula (Fig. 2G ) outer ramus with 4 + 5 teeth, apically entire, and two thick plumose stalks; inner ramus with three penicils, proximal one stout. Maxilla (Fig. 2H ) bilobate, inner lobe wider than outer lobe, with several thin and thick setae. Maxilliped (Fig. 2I ) basis trapezoidal, distal portion slightly wider than basal; palp apex with tufts of setae; endite shorter than palp, setose, apex with one conic penicil between two strong teeth, inner tooth long. Pereopod 1 antennal grooming brush composed by pectinate scales longitudinally on frontal face of carpus and propodus (Fig. 4A ), dactylus with one claw; pereopod 7 with water conducting scale rows. Uropod (Fig. 2B ) protopod surpasses distal margin of telson; endopod and exopod subequal in length, inserted at the same level, covered with pectinate scales.

Male. Pereopods 1, 6 and 7 (Figs 4A-C ) covered with setae; merus sternal margin with proximal tuft of setae. Pleopod 1 (Fig. 4D ) protopod trapezoid, apex tapering; exopod covered with setae, triangular with sinuous external margin; endopod as long as exopod, with narrow basal article and flagelliform distal article. Pleopod 2 (Fig. 4E ) exopod semi-oval, rounded distal margin, covered with setae; endopod of two articles, basal article quadrangular, shorter than exopod, distal article stout, apex with acute lobe directed outward. Pleopod 3 exopod (Fig. 4F ) trapezoid, covered with thin setae on the distal portion and along the inner margin. Pleopod 4 exopod (Fig. 4G ) rhomboid, wider than long, covered with thin setae. Pleopod 5 exopod (Fig. 4H ) ovoid, wider than long, covered with thin setae.

Etymology.

The epithet " Chaimowiczia tatus " refers to the "Tatus II project", an experiment of human permanency inside a cave held in 1987, conducted in Gruta do Padre cave. During the experiment, a group of speleologists stayed for 21 days inside the cave performing topographic and speleology surveys (Chaimowicz, 1987).

Ecological remarks.

Gruta do Padre comprises an extensive cave with 16,400 m of horizontal projection and is currently considered the fifth longest cave in Brazil ( Rubbioli et al. 2019). It presents two entrances and three distinct levels. A river flows in the lowest level, which is the most extensive. The main entrance comprises a huge rock shelter (Fig. 5A ) that connects to a descending set of flowstones (Fig. 5A, B ). Specimens of Chaimowiczia tatus sp. nov. were observed in a single chamber in the second level (ca. 500 m from the main cave entrance), in clayish sediment pools (Fig. 5C-E ). Two other troglobitic styloniscid species occur in this cave: one terrestrial ( Pectenoniscus santanensis Cardoso, Bastos-Pereira, Souza & Ferreira, 2020a) and one new amphibious species. A peculiar condition is observed regarding the distribution of the two styloniscid species. While one species is amphibious, occurring in both aquatic and moist terrestrial habitats, C. tatus sp. nov. was observed exclusively underwater. The ponds where C. tatus sp. nov. occurs are devoid of the amphibious species, suggesting they might avoid each other. There are dozens of ponds along the lower conduit formed by the river overflow or by percolating water (especially in the case of travertine pools), where hundreds of individuals of the amphibious species were observed. However, no specimens of C. tatus sp. nov. were observed in the lower level coexisting with the other styloniscid. The ponds in which specimens of C. tatus sp. nov. occur usually present the substrate full of traces made by these individuals (Fig. 5C ) indicating their high motility and activity. Since no visible organic matter was observed within the ponds (like bat guano or vegetal debris), they may be feeding on the substrate itself, which might be rich in microorganisms. Gruta do Padre Cave presents other troglobitic species: the beetle Coarazuphium tessai (Godoy & Vanin, 1990), the amphipod Spelaeogammarus santanensis Koenemann & Holsinger, 2000, and the millipede Phaneromerium cavernicolum Golovatch & Wytwer, 2004. All of them were discovered during the Tatus II experiment, demonstrating the relevance of this cave regarding the biota. Although some alterations were caused during the Tatus II experiment (in both the cave interior - a camping area was established inside the cave - and the external area), no impacts from past actions are currently visible. The external environment surrounding the cave was altered by the replacement of the native vegetation by pastures or crops. On the other hand, the inner portion of the cave is well preserved. Since the huge extension of the cave and the fact that only a few speleologists visit it each year (especially due to the difficult access), C. tatus sp. nov. does not seem to be currently threatened.

Figures

Figure 2. Chaimowiczia tatus sp. nov. Male A habitus, dorsal view B telson and uropod, dorsal view C antennula D antenna E right mandible F left mandible G maxillula H maxilla I maxilliped. Scale bars: 1 mm (A); 0.2 mm (B-I).

Figure 3. Chaimowiczia tatus sp. nov. Male A cephalon, frontal view B cephalon, dorsal view C pereopod 1 propodus, carpus and dactylus. Scale bar: 500 µm (A); 200 µm (B).

Figure 4. Chaimowiczia tatus sp. nov. Male A pereopod 1 B pereopod 6 C pereopod 7 D pleopod 1 E pleopod 2 F pleopod 3 exopod G pleopod 4 exopod H pleopod 5 exopod. Scale bars: 0.2 mm (A - H).

Figure 5. A Gruta do padre cave main entrance B rock shelter leading to cave main entrance C Pond where the species was collected D Substrate marked by the species activity E Living specimen of Chaimowiczia tatus sp. nov. with approximately 9 mm.