Cylindroniscus platoi

Fernandes, Camile Sorbo, Campos-Filho, Ivanklin Soares & Bichuette, Maria Elina, 2018, Cylindroniscus platoi (Isopoda: Oniscidea: Styloniscidae), a new cave-dwelling species from Lagoa Santa Karst, Southeastern Brazil, Zootaxa 4461 (3), pp. 411-420: 413-417

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Cylindroniscus platoi

n. sp.

Cylindroniscus platoi  n. sp.

Material examined. Holotype 1 ♂ (in micropreparations) ( LES 6125View Materials), CAMP _038 cave (44°0’21.280”W / 19°33’48.444”S), Minas Gerais, Pedro Leopoldo , 3–21 November 2014, leg. Spelayon Consultoria staffGoogleMaps  . Paratypes 1 ♂, 1 ♀ (both in micropreparations) ( LES 6118View Materials), CAMP _013 cave (44°0’28.322”W / 19°34’4.227”S), Minas Gerais, Pedro Leopoldo , 3–21 November 2014, leg. Spelayon Consultoria staffGoogleMaps  ; 3 ♂, 3 ♀ (part in micropreparations) ( LES 6127View Materials), CAMP _024 cave (44°0’36.663”W / 19°34’9.608”S), Minas Gerais, Pedro Leopoldo , 3–21 November 2014, leg. Spelayon Consultoria staff.GoogleMaps 

Diagnosis. Antennal flagellum of three articles; inner endite of maxillula with one penicil stout on distal margin plus two proximal penicils; male pleopod 1 exopod triangular, wider than longer; male pleopod 2 endopod with distal portion of second article stout, almost spherical in shape.

Description. Maximum body length: ♂ and ♀ 3 mm. Colourless. Outline of body as in Fig. 3A View Figure . Cephalon and pereon with granulated surface, pleon smooth with setae on margins ( Figs 2 View Figure , 3A–B, F View Figure ). Pereonite 1 epimera directed frontwards, 2–7 gradually more directed backwards ( Figs 2 View Figure , 3A–B View Figure ). Dorsum covered with tricorn-shaped scale setae and semi-circular scale setae on lateral margins ( Fig. 3C, D View Figure ). Cephalon ( Figs 2 View Figure , 3E View Figure ) with no antennary lobes, frontal line absent, suprantennal line bent downwards medially. Outline of pleon ( Fig. 3A, F View Figure ) continuous with that of pereonite 7; epimera of pleonites 3–5 without glandular pores and bearing setae on lateral margins. Telson  ( Fig. 3F View Figure ) twice as wide as long, lateral sides slightly concave, rounded apex.

Antennula ( Fig. 3G View Figure ) of three articles, distal article longest bearing 7–9 stout aesthetascs apically cleft. Antenna ( Fig. 3H View Figure ) with distal article of peduncle bearing one strong seta; flagellum of three articles subequal in length, apical organ with many free sensory setae.

Mandibles with strong incisive process, left mandible ( Fig. 4A View Figure ) with one penicil, right mandible ( Fig. 4B View Figure ) with two penicils. Maxillula ( Fig. 4C View Figure ) inner endite with one stout apical penicil and two lateral subapical penicils; outer endite of 4+3 simple teeth. Maxilla ( Fig. 4D View Figure ) inner lobe wider than outer lobe, covered with thick setae; outer lobe covered with thin setae. Maxilliped ( Fig. 4E View Figure ) endite subrectangular bearing one stout apical penicil and laterally covered with simple seta.

Uropod ( Fig. 5A View Figure ) protopod subrectangular, exopod longer than endopod bearing long setae, endopod inserted almost at the same level with one long seta.

Pereopods ( Fig. 5B–D View Figure ) bearing sparse setae on sternal margin of merus and carpus, pereopods 6 and 7 with water conducting system, pereopod 7 propodus bearing tuft of setae on distal tergal margin; dactylus with long dactilar seta apically cleft.

Male. Genital papilla ( Fig. 6A View Figure ) elongated, slightly enlarged on median portion, apical portion narrow. Pleopod 1 ( Fig. 6B View Figure ) exopod triangular, twice as wide as long; endopod of two articles, distal article twice as long as proximal article. Pleopod 2 endopod of three articles, distal article long and robust, distal portion stout, almost spherical in shape. Pleopod 3 exopod ( Fig. 6D View Figure ) almost losangular bearing five setae. Pleopod 4 exopod ( Fig. 6E View Figure ) subquadrangular with four setae. Pleopod 5 exopod ( Fig. 6F View Figure ) ovoid bearing three setae.

Remarks. Regarding that only C. flaviae  had male specimens described (see Campos-Filho et al. 2017a), comparisons with other species of the genus are limited. Nevertheless, Cylindroniscus platoi  n. sp. is readily distinguishable from the other species in the genus by the shape of the pleopod 2 endopod, which is stout and almost spherical on its distal portion. In having the dorsal surface granulated Cylindroniscus platoi  n. sp. resembles C. flaviae  ; however, it differs in having the antennal flagellum of three articles (vs. four in C. flaviae  ), maxillula inner endite with one stout penicil (vs. two in C. flaviae  ), male pleopod 1 exopod wider than long (vs. longer than wide in C. flaviae  ), male endopod 1 longer than exopod (vs. similar in length in C. flaviae  ), male endopod 2 with distal portion stout and semi-circular (vs. narrow and triangular in C. flaviae  ).

Considering that all species of Cylindroniscus  , despite the habitat of origin, are devoid of eyes and color, these traits cannot be considered as troglomorphisms for the group (sensu Christiansen 1962). The troglobitic and endemic status are attributed to Cylindroniscus platoi  n. sp. based on the fact that this species was found only inside of caves in a continuous limestone outcrop, which putatively allows subterranean dispersion. With the exception of C. flaviae  , an ecological evolutionary status for species of the genus found in caves is still lacking, denoting the need of morphological and field studies to raise the not-so-obvious troglomorphisms, which may be present in the troglobites of the genus. As proposed by Schmalfuss (1984), the granulated or tuberculated dorsal surface of Cylindroniscus platoi  n. sp. can be attributed as an adaptation to cope with the high humidity in the cave environment. This condition is more conspicuous when compared to C. seurati  , the only species collected outside caves, which shows the dorsal surface smooth.

Despite being an area of high scientific and cultural value, the Karst of Lagoa Santa has been threatened by the expansion of the metropolitan sprawl of Belo Horizonte and its satellite cities, including Pedro Leopoldo. Mining activities and the urbanisation have already caused groundwater pollution, loss of caves and its original vegetation ( Auler & Piló 2015). Although environmental impacts in the area are regulated because of the Environmental Protection Area of the Lagoa Santa Karst ( IBAMA 1998), the caves are near a mining pit, as can be seen in Fig 1 View Figure , and possibly suffer the impacts resulting from this activity. To Auler & Piló (2015) the creation of other preservation areas in the vicinity, including the Sumidouro State Park ( PESU) (created by the Law Decree n° 20.375 of 1980 from the state of Minas Gerais), are changing this framework towards the effective protection of a significant portion of the karst.

Living in this unique region and facing these threats, Cylindroniscus platoi  n. sp. is the first troglobite described for caves of Pedro Leopoldo, emphasizing the importance of the cave fauna of the region.

Etymology. The new species is named after the ‘Allegory of the Cave’ by the Greek philosopher Plato, in his work Republic (514–520 B.C.). This work reminds us of the importance of the scientific knowledge and its democratization.