Apodemus atavus Heller, 1936
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publication ID |
https://doi.org/ 10.4202/app.01074.2023 |
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persistent identifier |
https://treatment.plazi.org/id/1A1DEB1C-423F-8720-2832-6528FB15FD69 |
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treatment provided by |
Felipe |
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scientific name |
Apodemus atavus Heller, 1936 |
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Fig. 5A–D View Fig .
Material.—Two M1 (IPHES-BC-5, 11), and two m1 (IPHES- BC-6, 13). All from Lower Pleistocene, Barranco de los Conejos, Guadix-Baza Basin, Spain.
Measurements.—See Table 7.
Description.—In the M1, the t1 is slightly displaced backward with respect to the t2 and t3. The t1 has a posterior spur reaching basally the t4–t5 intersection in one specimen (IPHES-BC-5). The t2–t3 connection is higher than that of t1–t2. The t3 has a short posterior spur directed to the t5–t6 intersection. The t1bis and t2bis are absent. The well-developed, elongated t7 is connected to the t8, and separated from the t4. The t6 and t9 are connected. There is a reduced t12.
The m1 has a large, round tma. It is connected to the intersection of the two anteroconid lobes, forming a funnel in one specimen (IPHES-BC-13). The anteroconid complex is symmetrical. The lingual lobe of the anteroconid is connected to the protoconid–metaconid junction. There is no longitudinal crest. The labial cingulum is well developed. The oval posterior accessory cuspid (pac1) is similar in size to the tma. It is connected to the anterolabial face of the hypoconid. There are up to three additional accessory cuspids. The oval, lingually displaced posterior heel is variable in size.
Remarks.—The presence of t7 and t6–9 connection, the well-developed labial cingulum, and the absence of longitudinal crest in the studied specimens allow their ascription to the genus Apodemus . Apodemus gorafensis , Apodemus jeanteti , and Apodemus agustii are larger than the specimens from Barranco de los Conejos ( Michaux 1967; Pasquier 1974; Ruiz Bustos et al. 1984; Martín-Suárez 1988; Bachelet 1990; Piñero et al. 2017; Piñero and Agustí 2019, 2020; López-García et al. 2023). The studied material is close in size to Apodemus barbarae , but the presence of an individualized t7, and the complete union between the t6 and t 9 in the M1 rule out ascription to this species ( Weerd 1976). The size is also similar to that of Apodemus gudrunae , but again, the presence of a well-developed t7 precludes assigning the studied sample to this species (see Weerd 1976; Adrover et al. 1993; Piñero et al. 2018b). The small size, the presence of a large tma and the connection between the lingual lobe of the anteroconid and the protoconid–metaconid pair in the m1, and the separation between the t4 and t 7 in the M1 are typical traits of Apodemus atavus (see Heller 1936). Furthermore, the material from Barranco de los Conejos is close in size to Apodemus atavus from Tollo de Chiclana 1B ( Spain; Minwer-Barakat et al. 2005), Pedrera del Corral d’en Bruach ( Spain; López-García et al. 2023), Asta Regia 3 ( Spain; Castillo and Agustí 1996), Moreda 1A, 1B ( Spain; Castillo-Ruiz 1990), Alozaina ( Spain; Aguilar et al. 1993), Mas Rambault 2, Balaruc 2, Plà de la Ville, Lo Fournas 4 ( France; Bachelet 1990), Csarnota ( Hungary; Weerd 1976), Monte la Mesa ( Italy; Marchetti et al. 2000), Notio 1 ( Greece; Hordijk and De Bruijn 2009), Schernfeld ( Germany; Pasquier 1974), Węże, Rębielice ( Poland; Pasquier 1974), and Hambach ( Germany; Mörs et al. 1998), among other localities. Based on both morphological and biometrical criteria, the specimens from Barranco de los Conejos are attributed to Apodemus atavus .
According to several authors, Apodemus atavus and Apodemus dominans represent extreme phenotypes of a single species, Apodemus dominans being a junior synonym of Apodemus atavus ( Fejfar and Storch 1990; Martín-Suárez and Mein 2004; Minwer-Barakat et al. 2005; García-Alix et al. 2008; Colombero et al. 2014). Some authors considered Apodemus atavus as the direct ancestor of the living Apodemus sylvaticus ( Rietschel and Storch 1974; Fejfar and Storch 1990; Martín-Suárez and Mein 1998; Piñero et al. 2022).
Stratigraphic and geographic range.—Uppermost Miocene to Lower Pleistocene ( Rietschel and Storch 1974; Fejfar and Storch 1990; Colombero et al. 2014; López-García et al. 2023; among others). It geographic range includes much of the Palearctic region, from Western Europe to China ( Cai and Qiu 1993; Martín-Suárez and Mein 2004; Knitlová and Horáček 2017; Agustí et al. 2022a; among others).
Genus Castillomys Michaux, 1969
Type species: Castillomys crusafonti Michaux, 1969 , Layna, Pliocene.
Castillomys rivas Martín-Suárez and Mein, 1991 Material.—Eight M1 (IPHES-BC-1, 2; IPHES-BC-3, anterior fragment; IPHES-BC-4, fragmented; IPHES-BC-14–16; IPHES-BC-18, anterior fragment), one M2 (IPHES-BC-20), one M3 (IPHES-BC-19), three m1 (IPHES-BC-7, 9, 12), and four m2 (IPHES-BC-8, 10, 17, 21). All from Lower Pleistocene, Barranco de los Conejos, Guadix-Baza Basin, Spain.
Measurements.—See Table 8.
Description.—All the specimens have well-developed longitudinal crests, completing the connection among the tubercles of the crown. The M1 has the t1 displaced backward, and generally develops t1bis and t2bis. The posterior crests of the t1 and t3 are well developed and connected to the t4–t5 and t5–t6 intersections, respectively. There is no t7. The t4–t6, t9, and t8 are connected by a low crest. The t4–t8 crest is also low. The t12 is present as a small bulge between the t8 and t9.
In the M2, the t1 is connected to the t4–t5 intersection by a spur. The t1bis is present as a double t1. The round t3 is connected to the t5–t6 intersection by a narrow, low crest. The t7 is absent. The t4–t6, t9, and t8 are connected. There is a t4–t8 connection. The t12 is shown as a small salient between the t8 and t9.
The M3 has the t1 connected to the t5. The t3 is absent. There is a t4–t6 connection. The t9 is fused to the t8 forming a complex connected to the t6.
In the m1, the tma is absent. The anteroconid complex is slightly asymmetrical. The longitudinal crest is complete, being connected to the lingual part of the protoconid. The metaconid and entoconid are situated slightly anteriorly relative to the protoconid and hypoconid, respectively. The subtriangular or elongated posterior heel reaches the posterolingual base of the entoconid. The broad labial cingulum is separated from the protoconid by a valley. The oval or elongated pac1 is connected to the hypoconid by a spur. Another small accessory labial cuspid can be present.
In the m2, the large anterolabial cuspid is connected to the anterior side of the protoconid by a spur. The complete longitudinal crest may be connected to the metaconid–protoconid junction, or to the lingual side of the protoconid. The posterior heel may be oval or elongated. The labial cingulum is well developed and separated from the protoconid by a valley. There is a very small, low pac 1 in three out of four specimens. No other accessory cuspids are present.
Remarks.—The small size, the well-developed longitudinal crest on the m1 and m2, the absence of t7, and the presence of a posterior crest on the t1 and t 3 in the M1 and M2, are distinguishing features of Castillomys . The material from Barranco de los Conejos can be distinguished from Castillomys gracilis and Castillomys crusafonti by its larger size, and greater development of longitudinal connections both in upper and lower molars ( Michaux 1969; Martín-Suárez and Mein 1991). The complete connection among the tubercles of the crown, and the presence of a broad labial cinculum separated from the protoconid by a valley in the m1 and m2 are features present in the species Castillomys rivas . In addition, the specimens from Barranco de los Conejos lie within the size range of Castillomys rivas from its type locality (Loma Quemada-1; Martín-Suárez and Mein 1991). They also agree in size with Castillomys rivas from Pedrera del Corral d’en Bruach ( López-García et al. 2023), Quibas ( Piñero et al. 2015, 2022), Valdeganga 7 Martín-Suárez and Mein 1991), Mas Rambault 2 ( Aguilar et al. 2002), Orce 3, Venta Micena 1 ( Martín-Suárez 1988), Fuente Nueva 3 ( Agustí et al. 2010), and Tollo de Chiclana 10B ( Minwer-Barakat et al. 2005), among other localities. Accordingly, the specimens from Barranco de los Conejos are ascribed to Castillomys rivas .
The first appearance of the genus Castillomys presumably coincides with the beginning of the Pliocene ( Weerd 1976; Mein et al. 1990; Piñero and Agustí 2019; Piñero et al. 2018a, 2023), whereas it disappeared at the Early–Middle Pleistocene boundary ( Agustí et al. 1999). Martín-Suárez and Mein (1991) proposed the anagenetic evolutionary lineage Castillomys gracilis – Castillomys crusafonti – Castillomys rivas , which underwent an increase in size and better development of the longitudinal connections along the Pliocene and Early Pleistocene.
Stratigraphic and geographic range.—Early Pleistocene; Iberoccitan province, Spain ( Michaux 1969; Mein et al. 1978; Martín Suárez and Mein 1991; Minwer-Barakat et al. 2005; Piñero et al. 2020, 2023; among others). Castillomys rivas has been found in a number of Early Pleistocene localities from Spain and southern France. The oldest populations of Castillomys rivas have been identified in earliest Pleistocene localities, such as Tollo de Chiclana 10 and 10B (MN17; Guadix-Baza Basin, Spain; Minwer-Barakat et al. 2005) and Valdeganga 7 (MN17; Spain; Mein et al. 1978). The youngest record of this species has been reported from the late Early Pleistocene site of Cúllar-Baza B (Guadix-Baza Basin, Spain; Agustí et al. 1999).
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