Plesiosminthus margaritae, Freudenthal & Martín-Suárez, 2017

Freudenthal, Matthijs & Martín-Suárez, Elvira, 2017, A revision of European Plesiosminthus (Rodentia, Dipodidae), and new material from the upper Oligocene of Teruel (Spain), Palaeontologia Electronica 9 (1), pp. 1-25 : 6-8

Plesiosminthus margaritae n. sp.

Figure 3.1-12

zoobank.org/ 9B1B48B8-7527-453D-9031-F0D850E9627B

Type locality. Mirambueno 1, MP27, Spain.

Holotype. M2 dext., MIR1 193, Museo de Ciencias

Naturales, Universidad de Zaragoza.

Material. Collection Naturalis-Leiden: 21 m 1, RGM

558094–558114; 32 m 2, RGM 558115–558146; 41

m3, RGM 558147–558187; 1 P4, RGM 558307; 49

M1, RGM 558188–558236; 36 M2, RGM 558237–

558272; 33 M3, RGM 558273–558306. Collection

Zaragoza: 2 m 1, MIR1 164–165; 11 m 2, MIR1

166–176; 4 m 3, MIR1 177–180; 8 M1, MIR1 181–

188; 7 M2, MIR1 189–195; 3 M3, MIR1 196–197,

228.

Measurements. Appendix 1, Figure 4 .

Derivatio nominis. In honour of Dr. Marguerite

Hugueney, co-author of the first monographic paper on Plesiosminthus after the study by Schaub

(1930).

Diagnosis. Anteroconid of m1 small, without an anterolophulid. Ectolophid oblique. Mesoconid and mesostylid generally absent; when present, poorly developed. Protoconid hind arm of m2 transverse and low connected to the metaconid in half the cases, may be absent or short, or of medium length. Ectolophid oblique or, less frequently, longitudinal. Mesoconid and mesostylid like in m1. Protoconid hind arm in m3 the predominantly absent,

mesolophid generally long, may reach the border of the molar. Anterocone, anterostyle, and mesostyle in M1 generally absent. Protolophule in M2

anterior, frequently accompanied by a - complete or incomplete posterior connection.

Description. Number of specimens in brackets.

m1—anteroconid absent (3), small (11), or with cingulum (3); anterolophulid absent; metalophulid absent; protoconid hind arm transverse and low connected to the metaconid (4), transverse and high connected to the metaconid (9), bent and low connected to the metaconid (1), or bent and high connected to the metaconid (8); ectolophid longitudinal (1) or oblique (22); ectolophid complete (14), anteriorly interrupted (6), or isolated (2); mesoconid absent (16) or weak (4); mesosinusid open (19) or closed (3); mesolophid reaching the border of the molar (15) or ends in a mesostylid (6); ectomesolophid absent; hypolophulid anterior transverse (17) or transverse (5); hypoconid hind arm absent; posterolophid continuous (18) or interrupted (1); labial posterolophid absent (17) or small (2).

m2—labial anterolophid present; metalophulid absent (1), anterior complete (38), or connected to the anteroconid (2); protoconid hind arm absent (6), short free (6), transverse and low connected to the metaconid (20), transverse and high connected to the metaconid (2), medium-length and free (5), bent and low connected to the metaconid (2), or bent and high connected to the metaconid (1); ectolophid longitudinal (13) or oblique (29); ectolophid complete (41) or anteriorly interrupted (1); mesoconid absent (32) or weak (8); mesosinusid open (37) or closed (4); mesolophid reaching the border of the molar (37) or ends in a mesostylid (5); ectomesolophid absent; hypolophulid anterior transverse (41) or transverse (1); hypoconid hind arm absent (39) or short (2); posterolophid continuous; labial posterolophid absent (29), small (7), or strong (2).

m3—lingual anterolophid absent (2), short (2), or long (39); labial anterolophid long; metalophulid absent (5), connected to the anteroconid (8), to anterolophulid (23), to protoconid (4), or double (3); protoconid hind arm absent (28), short free (5), transverse and low connected to the metaconid (9), or long and ending free (1); sinusid open; sinusid narrow transverse (7), broad transverse (1), narrow backwards (32), or broad backwards (3); mesosinusid open (13) or closed (29); mesolophid absent (2), short (1), of medium length (5), long (22), reaching the border of the molar (11), or ends in a mesostylid (2); ectomesolophid absent; entoconid absent (13), small (24), or large (4); hypolophulid anterior oblique (7) or anterior transverse (35); hypoconid hind arm absent; posterosinusid open (4), half closed (17), or closed (21); shape short triangle (11), long triangle (7), or trapezoid (23); in four specimens there is a longitudinal connection metaconid-mesoconid.

M1—anterocone absent (46) or present (4); anterostyle absent (43) or present (5); anterolophule continuous; antecingulum absent (44) or present (10); protolophule double (1) or posterior (53); sinus open

(51), half closed (1), or there is an entostyle (1);

sinus strong forward (3), forward (50), or transverse

(1); mesosinus open; mesoloph reaching the border of the molar (52) or connected to a mesostyle (1);

entomesoloph absent (52) or short (2); metalophule anterior (6) or transverse (48); posterosinus large and open (44), small and open (6), or small and closed (1). M2—lingual anteroloph absent (11), weak (17), or strong

(11); protolophule anterior (10), anterior plus incomplete posterior connection (16), transverse (2), or double (15); sinus open (41) or there is an entostyle

(2); sinus strong forward (6) or forward (37); mesosinus open (40) or closed (1); mesoloph reaching the border of the molar, no mesostyle. Entoloph-protocone connection high (6), low (23), or interrupted

(13); metalophule anterior (27) or transverse (15);

posterosinus large and open. M3—lingual anteroloph absent (25) or weak (9); protocone is a distinct cusp (17) or a mere crest (17); protolophule absent (2), to anterocone (9), to anterolophule (14), transverse to axioloph (8), or double (1); sinus absent (15), very small (8), small

(5), or deep (7); neo-entoloph absent (2), interrupted

(5), low (4), or high (24); mesosinus open (30) or closed (3); mesoloph reaching the border of the molar (26) or connected to a mesostyle (7); old entoloph absent (10), curved spur (1), or complete

(24); axioloph absent (2), short posterior spur (1),

long posterior spur (7), or = old entoloph (25); centroloph absent; centrocone absent (31), present (1),

or on old entoloph (2); metacone absent (18) or present (16); posterosinus open (3) or closed (32).

Plesiosminthus margaritae n. sp. differs from P. moniqueae n. sp. by: the better developed posterior protolophule in M2, the general absence of anterocone and anterostyle in M1 and of the mesostyle in M1 and M2; the frequent absence of a protoconid hind arm in m3. Plesiosminthus margaritae n. sp. differs from P. bavaricus by: on average shorter molars; protoconid hind arm of m1 bent in less than half the cases (41% vs. 91%); the rare presence of an ectostylid/cingulum in m1; the on average shorter mesolophid in m3; the more frequently complete posterior protolophule in M2, the less frequently interrupted entoloph-protocone connection in M2 (31% vs. 100%). N.B. The two smallest M2 from MIR1 (RGM 558261 0.91 mm x 0.84 mm; RGM 558264 0.87 mm x 0.85 mm) may belong to a different species. The distribution in Figure 4 appears to be discontinuous.

Figures

FIGURE 3. Plesiosminthus margaritae n. sp. from Mirambueno 1 (occlusal views). 1, m1 sin., RGM 558099; 2, m2 sin., MIR1 168; 3, m3 sin., RGM 558149; 4, M1 sin., RGM 558200; 5, M2 sin., MIR1 189; 6, M3 sin., MIR1 196; 7, m1 dext., RGM 558105; 8, m2 dext., RGM 558138; 9, m3 dext., MIR1 178; 10, M1 dext., MIR1 187; 11, M2 dext., MIR1 193 (Holotype); and 12, M3 dext., MIR1 197.

FIGURE 4. Scatter diagrams of molar length (L) and width (W) of Plesiosminthus margaritae n. sp. from Mirambueno 1 (in mm). 1, m1; 2, m2; 3, m3; 4, M1; 5, M2; and 6, M3.

FIGURE 5. Scatter diagrams of molar length (L) and width (W) of Plesiosminthus cf. margaritae n. sp. from Vivel del Río 1 (in mm). 1, m1; 2, m2; 3, m3; 4, M1; 5, M2; and 6, M3.

FIGURE 6. Scatter diagrams of molar length (L) and width (W) of Plesiosminthus aff. conjunctus (cross) and Plesiosminthus sp. (circle) from Mirambueno 2A, compared with the distribution area (rectangle) of Plesiosminthus conjunctus molars from HERR8 (in mm). 1, m1; 2, m2; 3, m3; 4, M1; 5, M2; and 6, M3.

FIGURE 7. m1 length (1) and width (2) of Plesiosminthus species. The bars represent the minimum and maximum in mm, a tick marks the mean, and the number of specimens is given to the right.

FIGURE 8. m2 length (1) and width (2) of Plesiosminthus species. The bars represent the minimum and maximum in mm, a tick marks the mean, and the number of specimens is given to the right.

FIGURE 9. m3 length (1) and width (2) of Plesiosminthus species. The bars represent the minimum and maximum in mm, a tick marks the mean, and the number of specimens is given to the right.

FIGURE 10. M1 length (1) and width (2) of Plesiosminthus species. The bars represent the minimum and maximum in mm, a tick marks the mean, and the number of specimens is given to the right.

FIGURE 11. M2 length (1) and width (2) of Plesiosminthus species. The bars represent the minimum and maximum in mm, a tick marks the mean, and the number of specimens is given to the right.

FIGURE 12. M3 length (1) and width (2) of Plesiosminthus species. The bars represent the minimum and maximum in mm, a tick marks the mean, and the number of specimens is given to the right.