Platicrista borneensis Gąsiorek & Michalczyk, 2024

Gąsiorek, Piotr, Blagden, Brian, Morek, Witold & Michalczyk, Łukasz, 2024, What is a ‘ strong’ synapomorphy? Redescriptions of Murray’s type species and descriptions of new taxa challenge the systematics of Hypsibiidae (Eutardigrada: Parachela), Zoological Journal of the Linnean Society 202 (1), pp. 1-63 : 27-28

Platicrista borneensis Gąsiorek & Michalczyk sp. nov.

ZooBank registration: urn:lsid:zoobank.org:act:08931145-78C1-439F-85DD-2A48C3CA516B

Material examined: 10 individuals in total (for details, see Supporting Information, Table S1 ).

Type material: Holotype (slide MY.100.01 ) and eight paratypes (slides MY.090.01 , MY.091.02 , MY.100.01 , and MY.826.04 ) from Malaysia, Borneo, Sarawak, Gunung Mulu , The Main Trail (4°02 ʹ N, 114°48 ʹ E; ~ 60 m a.s.l.), moss from tree trunk in a primary rainforest, 27 July 2016, Gąsiorek coll., and Malaysia, Borneo, Sarawak, Bako Peninsula (1°43″16‘N, 110°27 ʹ 39″E; 107 m a.s.l.), moss from soil and tree trunk in a primary rainforest, 5 August 2017, Gąsiorek & Oczkowski coll., are deposited in the Institute of Zoology and Biomedical Research, Jagiellonian University, Kraków.

Description: Body white and elongate ( Table 7 ), with blunt cephalic part ( Fig.21A, B ). Cuticle smooth, without pores, wrinkling or granulation. Cribriform areas not visible under PCM. Legs short, and even legs IV poorly delimited from the caudal body end. Eyes absent in unmounted animals. Buccopharyngeal apparatus of the Platicrista type ( Fig. 21B ): OCA not visible under PCM, annulated pharyngeal tube shorter than rigid buccal tube, both being moderately wide; stylet supports embedded anteriorly on the buccal tube; furcae of the Platicrista type (cochlear); pharyngeal apophyses absent; pharynx oval, with two bar-like macroplacoids: the first distinctly shorter than the second (1 <2).

Claws of the Hypsibius type, delicate and slender ( Fig. 21C ). Accessory points not discernible on the primary branches of the external claws, but identifiable on the primary branches of the internal claws and only slightly separated from them. Septa between claw parts absent. Pseudolunulae absent. Median and posterior cuticular bars present ( Fig. 21A, C ).

Etymology: The name signifies the terra typica. An adjective in nominative singular.

Differential diagnosis: There are three congeneric species with cuticular bars on their legs: Platicrista brunsoni Miller and J.D. Miller, 2021 , Platicrista cheleusis Kathman, 1990 , and Platicrista ramsayi Marley, 2006 . Platicrista borneensis can be differentiated from them based on: • P. brunsoni , the presence of median bars (present in P. borneensis vs. absent in P. brunsoni ), the presence of polygonal sculpturing on the dorsum (absent in P. borneensis vs. present in P. brunsoni ), and the presence of indentation on the base of claws IV (absent in P. borneensis vs. present in P. brunsoni );

• P. cheleusis , the presence of median bars (present in P. borneensis vs. absent in P. cheleusis ), and the presence of polygonal sculpturing on the dorsum (absent in P. borneensis vs. present in P. cheleusis );

• P. ramsayi , the presence of median bars (present in P. borneensis vs. absent in P. ramsayi ).

Figures

Figure 21. Detailed morphology of Platicrista borneensis sp. nov. (PCM): A, holotype in ventral view (white arrowheads indicate median and posterior bars); B, buccopharyngeal apparatus in toto (paratype); C, claws II (paratype). Scale bars are in micrometres.