Pseudorhapydionina chiapanensis Michaud et al., 1984

SIMMONS, MICHAEL & BIDGOOD, MICHAEL, 2023, “ Larger ” Benthic Foraminifera Of The Cenomanian. A Review Of The Identity And The Stratigraphic And Palaeogeographic Distribution Of Non-Fusiform Planispiral (Or Near-Planispiral) Forms, Acta Palaeontologica Romaniae 19 (2), pp. 39-169 : 117

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.