Ranina tejoniana Rathbun, 1926

Pasini, Giovanni & Garassino, Alessandro, 2017, A preliminary review of the fossil species of Ranina Lamarck, 1801 (Decapoda, Brachyura, Raninidae), with systematic remarks, Natural History Sciences 4 (1), pp. 43-72 : 61

Ranina tejoniana Rathbun, 1926

Fig. 15

Ranina tejoniana Rathbun, 1926: 90 , fig. 1, Pl. 22, figs. 1, 2.

Ranina tejoniana - Glaessner 1929: 363. – De Angeli et al. 2009: 120. – Schweitzer et al. 2010: 74. – De Angeli & Beschin 2011: 13. – Van Bakel et al. 2012: 209. – Karasawa et al. 2014: 260.

Hela tejoniana - Lőrenthey in Lőrenthey & Beurlen 1929: 109.

Type material: holotype, CASG 2815 .

Type locality: west side of Tecuya creek , California, USA; Tejon Formation .

Geological age: Paleogene (Eocene series).

Examined material: holotype.

Description by Rathbun (1926): “ Carapace very convex from side to side, nearly flat from front to back; sides of carapace as preserved very arcuate, armed with two depressed spines the origins of which are to be seen on the left side; the posterior of the spines, at the anterolateral angle, is smaller than the other; its cross-section is a little more than twice as long as wide, the cross-section of the larger is three times as long as wide, and the distance between them is equal to the length of the smaller cross-section; the longitudinal distance of the posterior end of the base of the posterior spine from the outer orbital angle is greater than the transverse distance of that angle from the line of the greatest width of the carapace; only two orbital teeth, the two outermost, are visible; both are truncate, separated by an open suture, inclined a little inward; outer margin of outer tooth very oblique and slightly convex, a point at its outer corner has been broken off; similar spines may have been present at the corners of the second tooth; very little of the true outer surface of the carapace remains; a small piece near the anterior middle is smooth, while another piece near the lateral spines bears a few granules directed forward; underlying surfaces are granulate, the granules thinning out toward the middle; the pterygostomian regions are swollen; the merus of the left outer maxilliped is fairly complete; it is rather short and broad with a deep inner groove; the outer margin of the exognath is very convex; the episternum is subcircular, broadly pointed at the extremity and invaginated in the first sternal somite from which it is separated by a narrow fissure on each side; The first somite is characteristically broad, the lateral extremities have not been uncovered. ”

Discussion. Rathbun (1926: 90) described R. tejoniana by a sole incomplete carapace preserving partially some dorsal and ventral parts. Indeed, the original dorsal exocuticle is very poorly preserved, the fronto-orbital margin and anterolateral spines are incomplete, and rostrum lacks. Just the sternum shape shows the general characters of Raninidae sensu stricto. In conclusion, the inability to recognize the diagnostic characters of Ranina questions the placement of tejoniana within this genus.

Figures

Fig. 15 - Ranina tejoniana Rathbun, 1926; holotype, CASG 2815.A) Dorsal view. B) Ventral view. (x 1.4).