Pseudorhapydionina chiapanensis Michaud et al., 1984

Reference Illustration & Description

Michaud et al. (1984), Pls. 1 & 2 (not 11-14), p. 35-37.

Pseudorhapydionina chiapanensis is similar in respects to both P. dubia and P. laurinensis . Michaud et al. (1984) outlines the main differences as P. chiapanensis having a thicker wall and less depressed sutures compared with P. laurinensis and a more parallel-sided seriate portion compared with P. laurinensis which is more flaring. It has somewhat more chambers in the seriate portion than P. dubia . Consorti et al. (2016b) notes it has fewer internal septula in the seriate portion than P. dubia and P. laurinensis, and which are thick, medium length and thickened at the base. See the Species Key Chart (Appendix) for diagnostic and other characteristics.

Stratigraphic Distribution

Early – late (but not latest) Cenomanian.

Originally described from the early – middle Cenomanian of southern Mexico by Michaud et al. (1984) who associated the new species with Rotalipora apenninica (Renz) (= Thalmanninella appenninica) (late Albian – lower late Cenomanian; Bidgood & Simmons, 2022). However, T. apenninica is not illustrated, so there is something of a question mark over the oldest age of P. chiapanensis . Aguilera-Franco (2000, 2003) associated P. chiapanensis with P. dubia which she stated was a middle – late Cenomanian species. Aguilera-Franco & Allison (2004) placed the extinction of P. dubia within the late Cenomanian.

Cenomanian Paleogeographic Distribution

Central America/Caribbean.

This species was originally described and illustrated from the Chiapas region in the far south of Mexico (Michaud et al. 1984) and has subsequently only been reported from that region (i.e., the Maya Block), including Guatemala. Records include from the Guerrero-Morelos Platform (Aguilera-Franco et al., 2001; Aguilera-Franco, 2000, 2003 (illustrated); Aguilera-Franco & Romano, 2004; Aguilera-Franco & Allison, 2004; Bomou et al., 2019). Other records from southern Mexico include Michaud & Fourcade (1989), Rosales-Dominguez et al. (1997, 1998 illustrated); Cros et al. (1998) and Martens & Sierra-Rojas (2021). Records from Guatemala include Michaud et al. (1992); Fourcade et al. (1999); Moeschler (2009, illustrated); Caceres Flores (2016, illustrated) and Radmacher et al. (2021, illustrated). It was not reported by Omaña et al. (2012, 2019) from central Mexico which suggests a very restricted area of distribution.