Tanidromites schweitzerae, Starzyk, 2016

Starzyk, N, 2016, Three new species of the genus Tanidromites (Decapoda: Brachyura: Tanidromitidae) from the Late Jurassic (Oxfordian) of Poland, Palaeontologia Electronica 19 (3), pp. 1-14 : 9-11

Tanidromites schweitzerae n. sp.

Figures 2 , 5

zoobank.org/ 52BB1CE6-3303-4980-BE15-ECA9B86D3521

Diagnosis. Species reaching relatively large size – maximum carapace width is 14.75 mm. Carapace is flattened, with parallel lateral borders. AtC distance is very long (0.33-0.44 of RtC distance). Rostrum is short (R/RtC≤0.3) with a blunt tip. Augenrest is long (length is 0.75x width), protected only by suborbital margin, which extends beyond upper orbital margin and is strongest among all TABLE 2. All species of the genus Tanidromites with their respective habitats (information from Crônier and Boursicot, 2009; Fraaije et al., 2013; Hyžný et al., 2011; Müller et al., 2000; Robin et al., 2015; Schweigert and Koppka, 2011; Schweitzer and Feldmann, 2010; Starzyk, 2015a).

Species Age Habitat

T. sculpta Early Oxfordian to Late Kimmeridgian

T. scheffnerae Early Oxfordian to Late Kimmeridgian

T. etalloni Middle to Late Oxfordian

T. alexandrae Early to Late Oxfordian

T. insignis Early Oxfordian to Early Kimmeridgian

T. lithuanicus Middle Callovian

T. montreuilense Early Callovian

T. raboeufi Late Bathonian

T. richardsoni Bajocian shallow sponge- microbial mounds shallow sponge- microbial mounds ( Poland, Germany)

shallow sponge- microbial mounds ( Poland)

shallow sponge- microbial mounds ( Poland)

non reefal habitat associated fauna sparse; brachiopods, bivalves and crinoids ( Slovakia) shallow sponge- microbial mounds ( Poland, Germany)

shallow non reefal habitats associated with benthic macrofauna ( Lithuania)

lower offshore environment, close to or below storm wave base, with water depth 50-80 m, associated with benthic fauna ( France)

carbonate muddy buttoms ( France)

shallow non reefal habitats associated with benthic macrofauna ( Great Britain, Germany)

T. maerteni Early Bajocian shallow non reefal habitats associated ( France)

species of the genus. Cervical pits are rounded. Hepatic pores and hepatic tubercles are absent.

Comparison. Tanidromites schweitzerae differs from other species of Tanidromites significantly. It has a unique shape of the augenrest, long with an extended suborbital margin. The rostrum is also different, short (R/RtC≤0.3) with a blunt tip. Epibranchial regions are strongly elongated, not round as in other species of the genus.

Etymology. The trivial name is dedicated to Carrie E. Schweitzer, an outstanding specialist of fossil decapods.

Material

Type material. Holotype: I-F / MP/ 4515 /1534/08; type locality: Niegowonice; age: Middle-Late Oxfordian. Coll.: I.K. R. Borek.

Paratype. I-F / MP/ 6249 /1588/11; locality: Niegowonice. Coll.: I.K. R. Borek .

Additional material. Specimen from Niegowonice: I-F / MP / 4562 /1534/08. Coll.: I.K. R. Borek.

Total number of specimens. 3.

Dimensions. Maximal width across the epibranchial region is 14.75 mm.

Description. The carapace is flattened ( Figure 5.5 ). Lateral borders are smooth and parallel. The AtC distance is very long (0.33-0.44 of the RtC) ( Figures 2 , 5.1, 5.6, 5.7 ).

The rostrum is short (R/RtC≤0.3) with a blunt tip. The axial groove is shallow; it does not reach the anterior border of the rostrum. The rostrum is best visible on the specimen 4515 ( Figure 5.1, 5.2 ). The augenrest is long (length is about 0.75 of the width) ( Figures 2 , 5.2-4 ). Upper and suborbital margins are smooth without any spines or incisions. The suborbital margin is extending beyond the upper orbital margin, strongest of all the species of the genus. The anterior groove is not visible.

The mesogastric region is distinctly bordered by grooves in the anterior and posterior part, weaker in the middle. The anterior (narrow) and posterior (wide) part of the region are more or less the same length. There is an incision in the posterior margin of this region. Cervical pits are rounded. Mesogastric scars are elongated, strongly developed, positioned on both sides of this incision, and extend across the entire posterior border of the mesogastric region. Proximally they are accompanied by a parallel pair of smaller scars which are very weakly visible.

Protogastric and hepatic regions are not differentiated. Hepatic pits and hepatic tubercles are absent. Epigastric regions are strongly elongated. The tubercle on the urogastric region is absent.

The cardiac region is weakly preserved only on specimen 4562. There are two tubercles in the anterior part and one in the posterior part.

The epibranchial region is more convex, and branchial region more flattened. The epibranchial region is much shorter than branchial and hepatic regions.

The cervical groove is deep. The branchio-cardiac groove is deep on the lateral sides (parallel to the cervical groove), the middle part is more shallow but also distinct.

There is no ornamentation on the carapace. The cuticle is not preserved on any of the speimens.

Figures

FIGURE 2. Anterior part of the carapace and the augenrest in Tanidromites spp. The area of augenrest is shaded.

FIGURE 5. Tanidromites schweitzerae n. sp. 1, holotype (#4515, Niegowonice); 2, specimen (#4562, Niegownice); 3, lateral view (#4562, Niegowonice); 4, rostrum (holotype #4515, Niegowonice); 5, augenrest, view from above (holotype #4515, Niegowonice); 6, specimen (#6249, Niegowonice). Scale bars equal 1 mm.