Kilianicaris lerichei Van Straelen, 1923

Laville, Thomas, Forel, Marie-Béatrice & Charbonnier, Sylvain, 2023, Re-appraisal of thylacocephalans (Euarthropoda, Thylacocephala) from the Jurassic La Voulte-sur-Rhône Lagerstätte, European Journal of Taxonomy 898 (1), pp. 1-61 : 15-22

Kilianicaris lerichei Van Straelen, 1923

Figs 5B, 6–9

Kilianicaris lerichei Van Straelen, 1923a: 434–435 , pl. XIV figs 4–5.

Kilianicaris lerichei – Secrétan & Riou 1983: 84, pl. III figs 1–4. — Secrétan 1985: 386–387, fig. 2e. — Schram et al. 1999: 772. — Charbonnier 2009: 205–206, figs 249, 337, 367, tab. 14. — Charbonnier et al. 2010: 115, 117, 121, fig. 5c, tabs 1–2; 2014: 375, fig. 4b, tab. 1. — Schram 2014: 353. — Ji et al. 2017: 174. — Rak et al. 2018: 268. — Van Roy et al. 2021: 1737. — Schram & Koenemann 2022: tab. 41.2.

Material examined

Holotype

FRANCE • La Boissine, La Voulte-sur-Rhône, Ardèche, France; Callovian, Middle Jurassic; OSUG-UJF-ID.11545.

Paratype

FRANCE • same collection data as for holotype; OSUG-UJF-ID.1752.

Additional material

FRANCE • 48 specs; same collection data as for holotype; MNHN.F.A29246, A29253, A29301 to A293016, A29318, A29374, A29375, A53334, A53335, A53338, A53339, A53342, A83991 to A85013, A84073, R50942 , R50961 , R50967 , R50969 , R50972 , R50973 , R50975 , R50976 • 1 spec.; same collection data as for holotype; OSUG-UJF-ID.1751 • 3 specs; same collection data as for holotype; MSNM i7593, i7596, i20704 .

Measurements

See Table 2.

Description

Shield morphology

Rounded shield in lateral view with a straight and sub-vertical anterior margin, an antero-dorsal corner expressed as a large, rounded and horizontal rostrum, a slightly convex dorsal midline bearing a dorsal carina in its posterior third ( Fig. 6). Presence of serrations along the first two thirds of the dorsal midline, until the dorsal carina ( Fig. 6H–I). Postero-dorsal corner expressed as a small spine; straight and vertical posterior margin ending in a rounded postero-ventral corner; ventral margin divided into a posterior half steeply descending antero-ventrally and an anterior one ascending antero-dorsally; both parts merged approximately at mid-length; rounded antero-ventral corner. Rim of all free margins forming a marginal fold.

Shield macro-ornamentation

Dorso-lateral carina protruding from the posterior margin, running straight until the anterior third of the shield and forming a depression ( Figs 6–7); carina then ascending to the dorsal midline and merging with the dorso-lateral carina from the other side of the shield; carina associated with a row of at least 19 pores (d = ~ 0.5 mm) in its posterior part ( Fig. 8H–K). Marginal fold delimited by a ventro-lateral groove ( Fig. 6C–D).

Sensory structures

Oval, stalked compound eyes protruding from the anterior margin and occupying the entire margin ( Figs 7F–G, 9E, G).

Cephalic appendages

Cephalic appendages not preserved.

Raptorial appendages Presence of three pairs of raptorial appendages recognised by preservation of muscles, protruding from the ventral margin ( Figs 9H–I, 11). Raptorial appendages consisting of two parts: a proximal postero-ventrally oriented and a distal one, antero-ventrally oriented. Articulation between both parts forming an elbow.

First pair of raptorial appendages ( Fig. 9A–D), the shortest, consisting of a proximal part with two podomeres: a rectangular podomere 1 being 3.4 times as long as wide; a stout podomere 2 being 5.9 times as long as wide. Distal part of the appendages formed by three podomeres: podomere 3 being 4 times as long as wide; podomere 4 being 5.6 times as long as wide and bearing two medial spines; podomere 5, the most distal and shortest one, being 4.8 times as long as wide.

Second pair of raptorial appendages consisting of a proximal part with two podomeres ( Fig. 9): podomere 1 not well preserved; podomere 2 being 4.7 times as long as wide ( Fig. 9A–B, D). Distal part of the appendage consisting of three podomeres: podomere 3, the longest, being 5.2 times as long as wide and bearing two medial spines; podomere 4 being 5.3 times as long as wide and bearing four medial spines; podomere 5 being 3.5 times as long as wide and ending distally in a cluster of five long spines, the medial one being the smallest.

Third pair of raptorial appendages, the longest, consisting of a proximal part with two poorly preserved rectangular podomeres ( Fig. 9). Distal part consisting of three podomeres: podomeres 3 being 4.8 times as long as wide; podomere 4 being 6.1 times as long as wide; podomere 5 being 5.3 times as long as wide and ending in a cluster of two spines.

Oval structure

Long oval structure, protruding from the anterior part of the ventral margin, between raptorial and trunk appendages ( Fig. 9E–F).

Posterior trunk

Eleven, elongate rectangular structures (i.e., pleural part of posterior trunk segments) surrounding a long rectangular structure (i.e., possible tergal part; Fig. 8A–D). Pleural parts slightly curved downward at their distal end ( Fig. 8D). Last pleura thinner than the others. Posterior extremity of the trunk expressed as a rhomboidal element (i.e., telson) bearing a rounded structure, formed by two circular parts ( Fig. 6C– D): an outer one, delimiting the entire feature, and an inner smaller one.

Posterior trunk appendages

Eleven pairs of trunk appendages, postero-dorsally oriented, protruding from the posterior part of the ventral margin ( Fig. 8). First ten appendages formed by two parts: a square-shaped proximal one with a rounded distal margin and a styliform distal one ( Fig. 6E). Last pair of trunk appendages formed by two paddle-like parts and being longer than the rest ( Fig. 8A–B).

Gills

Eight long lamellar gills preserved under the central part of the shield below the dorso-lateral carina ( Fig. 6H–I). Gills with an elliptic shape, becoming arcuate near the dorsal midline.