Deinogalerix samniticus, Savorelli, Andrea, Masini, Federico, Mazza, Paul P. A., Rossi, Maria Adelaide & Agostini, Silvano, 2017

Savorelli, Andrea, Masini, Federico, Mazza, Paul P. A., Rossi, Maria Adelaide & Agostini, Silvano, 2017, New species of Deinogalerix (Mammalia, Eulipotyphla) from the late Miocene of Scontrone (Abruzzo, central Italy), Palaeontologia Electronica 11 (2), pp. 1-26 : 9-16

Deinogalerix samniticus sp. nov.

Figure 5 , Figure 6

zoobank.org/ 50CCEB68-BD93-4783-B342-293716175377

Diagnosis. Medium-sized Deinogalerix with proportionally very small p3 and large p4, p4 as long as m1. Trigonid of m1 broad, with mesiolingual bulge ( Figure 4.3-4 ) dipping downward and protruding lingually. M3 with well-developed parastyle. Strong and continuous mesiolabial cingulum in m2. P3 narrow, with relatively small protocone. In p4 paraconid imperfectly defined and trigonid valley closed lingually ( Figure 4.5-6 ).

Differential Diagnosis. Deinogalerix samniticus sp. nov. differs from all the other species of Deinogalerix by having proportionally a smaller p3 and a larger p4. Compared to D. koenigswaldi , D. samniticus sp. nov. has smaller overall size; smaller p3, m1, and m2; cheek teeth lower-crowned, imperfectly divided protocone-hypocone in P3 ( Figure 4.7-8 ); lower protocone in P4; more acute anterolabial corner in M3; lingually-closed trigonid basin and less-defined paraconid in p4; m1 with broad, trigonid not concave lingually, and with mesiolingual bulge dipping downward and protruding lingually; strong and continuous mesiolabial cingulum in m2; labially-prominent hypoconid in m3.

Deinogalerix samniticus sp. nov. differs from D. freudenthali by being larger sized, but also by possessing: larger p4 and m1; slightly more bunodont teeth; M3 with faint protoconule and more developed parastyle; trigonid of m1 with slightly lower lingual enamel wall and mesiolingual bulge dipping downward and protruding lingually; m2 with longer mesiolabial cingulum.

Deinogalerix samniticus sp. nov. differs from D. masinii by having: larger teeth (especially p4 and m1); smaller protocone, imperfectly divided protocone-hypocone and not well defined parastyle in P3; faint protoconule and more developed parastyle in M3; stronger and longer mesiolabial cingulum in m2.

Etymology. After the Samnites, an Italic people living in Samnium, the ancient region where Scontrone is located. Because the genus Deinogalerix is masculine ( Zijlstra and Flynn, 2015), the species name is treated here as masculine.

Synonymy. 2008, Deinogalerix freudenthali, Mazza and Rustioni , p. 209, figure 6. 2013, Deinogalerix freudenthali, Villier et al. , p. 64.

Material. Holotype: SCT 246, fragment of horizontal ramus of left hemimandible, still partly embedded in rock, preserving p3, p4, alveoli of p2, and most of the molar row, except m1, which is largely broken ( Figure 5.1-2 , Figure 6 ). Paratypes: fragmental right maxillaries SCT 232, with M3 and postero-lingual portion of M2 ( Figure 5.8 ), and SCT 19,

SAVORELLI ET AL.: DEINOGALERIX FROM SCONTRONE with complete P3 and fragmented P4; left m1 SCT 347.

Type Locality. Outskirts of Scontrone , southern border of the National Park of Abruzzi, L’Aquila, central Italy (41°45′15.54″N, 14°2′13.14″E) .

Horizon. Scontrone Member, Lithothamnion Limestone.

Age. Lower Tortonian (lower upper Miocene) ( Patacca et al., 2008b).

Measurements. See Table 2.

Description SCT 246 ( Figure 5.1-2 ). Fragment of horizontal ramus of left hemimandible still partly embedded in rock. Specimen broken in front of p2 alveoli and aborally to m3, but still preserving p3, p4, alveoli of p2, and most of the molar row, except m1, whose dental crown is largely broken. Mesial root of p2 slightly smaller than distal one. Tooth presumably somewhat smaller than p3 based on relative proportion of roots. In ventral view (specimen not observable in medial view) distal end of mandibular symphisis extended to mesial root of p3. Mental foramen located under mesial root of p3 and elongated mesially by groove. Horizontal ramus particularly thick latero-medially under molar section.

p3. Unworn, blunt, fairly low-crowned, dominated by protoconid triangular and symmetrical in side view. Metaconid absent. Labially, protoconid relatively swollen at the base. Two roots apparently straight and not divergent mesio-distally from one another. In occlusal view crown with sub-oval outline and with talonid represented by blunt and small cuspule, prominent disto-lingually. p3 narrower and markedly smaller than p4 ( Table 2) and separated from alveoli of p2 by short diastema.

p4. Moderately worn, large, and massive, quite more massive and larger than p3. Occlusal profile sub-oval, slightly wider distally, distal margin of tooth straight and transverse labio-lingually to horizontal ramus. Crown formed mesially by three fairly low and blunt cuspids, i.e., paraconid, protoconid, and metaconid. Protoconid dominant, metaconid somewhat lower than protoconid. Cleft between protoconid and metaconid clearly visible distally. Paraconid robust and low mesially. Protoconid connected with paraconid by blunt and low paralophid. Trigonid valley roundish, very shallow, and delimited lingually by very blunt and robust mesial border of metaconid (premetacristid?) and postparacristid. Distal side of crown slightly concave, distal cingulum very inclined labially and bearing small cuspule disto-lingually. Metaconid with bulbous disto-lingual mesostylid fused with cingulum.

m1–m3. Molars in typical fashion of Deinogalerix . Crown of m1 almost completely broken, with only entoconid, mesio-labial part of cingulum, and general outline of crown preserved. m2 and m3 largely visible, except entoconid of m2 and part of lingual enamel wall and of entoconid of m3, still embedded in rock. m1 largest tooth (approximately same length as p4) with very elongated trigonid. m2 and m3 quite worn. m2 much smaller and with shorter trigonid than m1, m3 slightly shorter, but quite more slender than m2. m2 with strong continuous mesial and labial cingulum prolonged distally to base of hypoconid. m3 with relatively narrower talonid than m2, hypoconid prominent labially, robust mesial cingulum, small labial cingulum at hypoflexid, from which issues very small enamel pillar.

Specimen SCT 347 ( Figure 5.3-5 ). Two-rooted left m1, well preserved, but rather worn. Marked disproportion between trigonid and talonid, typical of Deinogalerix . Trigonid with dominant, high and continuous, blade-like paralophid, formed by fusion of paraconid crest and preprotocristid, carnassial notch lacking. Lingual wall of trigonid high. Mesial part of lingual enamel wall between paraconid and metaconid (i.e., postparacristid) slightly protruding lingually forming a mesiolingual bulge ( Figure 4.3- 4 ) and dipping downwards towards collar. Upper margin of lingual enamel profile indented by wear at distal end of postparacristid. Metaconid and protoconid transversally aligned in occlusal view. Talonid narrower and much lower than trigonid. Hypoconid low and connected mesially with protoconid by cristid obliqua and lingually with entoconid by postcristid. Entoconid slightly higher than hypoconid. Hypoconulid absent. Presence of faint labial cingulum. Weak and short distal cingulum, not connected with postentocristid. Enamel much thinner in trigonid than in talonid. Mesial root much larger than distal root.

Specimen SCT 19 ( Figure 5.6-7 ). Fragmental right maxillary with complete P3 and fragmented P4.

P3. Bulbous tooth with typical Deinogalerix morphology. Trapezoidal outline, with labio-distal margin slightly inclined lingually. Crown very low and blunt, dominated by large and high paracone, placed in labial position. Shallow depression separating paracone from small, distally prominent metastyle (metacone of Villier and Carnevale, 2013). Tooth elongated mesially by shouldershaped parastyle. Lingual side of tooth formed by protocone-hypocone complex. Small protocone and large hypocone, separated by very shallow depression, which is rapidly obliterated by wear ( Figure 4.7-8 ). Based on wear pattern, protocone apparently slightly higher than hypocone. Hypocone bulbous, elongated and declining gently towards distal margin of crown, where it prolongs in cingular fashion. Lingual root with faint furrow not extended to lingual enamel wall, which appears complete.

P4. Only mesio-lingual half of tooth preserved. Larger than P3, with small mesio-lingual protocone. Differs from P3 by having shallow notch between protocone and crest-like hypoconal structure. Notch opens in valley between paracone and lingual cusps. Evident groove in lingual root, which corresponds to separation between protocone-hypocone.

Specimen SCT 232 ( Figure 5.8 ). Fragmental right maxillary, with M3 and postero-lingual portion of M2.

M2. Hypocone only cusp preserved. Mesial arm of hypocone connected with distal arm of protocone, distal arm of hypocone lacking. Metaconule partially preserved and well developed, placed in more mesial position than hypocone. Fragment of distal arm of metaconule apparently still preserved. Short entocingulum in valley between hypocone and protocone. Protocone and metaconule separated. Enamel thick.

M3. Sub-triangular outline. Mesial margin almost straight, disto-labial margin markedly arched, lingual margin slightly concave. Tooth somewhat broader than long. Protocone larger than all other cusps of tooth, and prolonged labially in narrow preprotocrista, which bears very reduced protoconule extended towards antero-lingual corner. Paracone connected with well-developed parastyle. Parastyle projected mesiolabially and labial margin of paracone slightly concave. Angle between mesial and labial margins of crown acute. Metacone strongly shifted to disto-lingual position, disto-labial part of tooth with distal arm of paracone and metacone joined to form continuous and arched crest, ending in inflated metastylar crest, separated from distal arm of protocone. Trigon valley deep and opened lingually. Very short entocingulum at outlet of the trigon valley. Short mesial cingulum. Protocone with flat wear surface. Enamel thick.

Comparison. The specimens from Scontrone have the typical characters of the genus: very large size, enlarged P3, P4, p3, p4, and trigonid of m1, very reduced m2 and m3, bunodont P3 and p4, well-developed metastylar crest in M3. Nonetheless, a number of differences exclude these teeth from those of all the known species. In particular Deinogalerix samniticus sp. nov. has a set of unusual dental proportions. Its middle-sized mandible bears a proportionally very large p4 (as large as those of D. intermedius and D. koenigswaldi ), smaller p3 (in the size ranges of D. freudenthali , D. minor , and D. brevirostris ), and large m1 and M3 (see Figure 7 , Figure 8 , Table 3, Table 4, Table 5).

Morphologically, the occlusal outline of p3 is somewhat less stretched disto-lingually than in the other species. The crown of p3 is lower than in D. koenigswaldi (RGM 179147, 177778, 177779) and than in the specimens of Deinogalerix sp. from fissures F8 and P81D.

In p4, the difference in height between the protoconid-metaconid complex and the paraconid is similar to that visible in the p4s of Deinogalerix freudenthali from F15 and D. masinii ; it is somewhat lesser in the p4s of the other species of Deinogalerix . The paraconid is also less well-identified than in other species, but it is connected with the metaconid and protoconid, similarly to D. freudenthali from F15. In contrast, the paraconid tends to be more isolated in all the other species ( D. masinii included). In labial view, the profile of the distal face of the protoconid is less steep than in D. koenigswaldi and closer to D. freudenthali from F15.

The lingual side of the m1 of Deinogalerix samniticus sp. nov. is characterized by the downward dip of the enamel margin of the mesiolingual bulge, which causes an unusual wear pattern. In all the other species but Deinogalerix masinii , this enamel profile is continuous and straight. In D. masinii the mesiolingual bulge never dips downward and ligually as much as in D. samniticus (Villier, personal commun., 2015). Because of the mesiolingual bulging, in occlusal view the trigonid of m1 of D. saminiticus appears somewhat broader than those of the m1s of most of the other species, which in contrast have an outline more concave lingually. Without detailed descriptions of this feature at hand, inspection of Villier et al.'s (2013) figure 3 suggests that also the m1 of D. masinii has a broad trigonid. m1 is relatively lower-crowned than in the more advanced species (e.g., D. koenigswaldi ). In D. samniticus sp. nov. the talonid is proportionally longer than in D. koenigswaldi . It does not present a mesial and labial cingulum at the base of the trigonid, as in the other species except D. masinii .

The m2 of Deinogalerix samniticus sp. nov. has a strong and continuous mesio-labial cingulum that extends distally to the base of the hypoconid. A similar, but shorter cingulum is possessed by all the small species of Deinogalerix (i.e., D. freudenthali and D. masinii ). This cingulum is generally weaker and discontinuous, and only sporadically uninterrupted (i.e., PU 100044: Villier and Carnevale, 2013) in D. koenigswaldi .

The m3 of Deinogalerix samniticus sp. nov. is bounded by a stronger cingulum than in the other species. In D. koenigswaldi this cingulum is virtually absent. m3 of D. samniticus sp. nov. has a hypoconid prominent labially, similar to that of D. freudenthali and D. masinii . In contrast, D. minor and D. koenigswaldi have a less prominent hypoconid, which gives the tooth a more rounded disto-labial outline.

P3 is lower-crowned than in the other species. It is proportionally somewhat narrower than in D. masinii and D. koenigswaldi . The protocone is very small. It falls, dimensionally, at the lower end of the size ranges of the genus. RGM 177982 (paratype of D. intermedius ) and a specimen from fissure Pirro 81/D (P81/D-026) possess P3s with protocones of approximately the same size, whereas D. masinii has P3s with the proportionally largest protocones of the genus. Accessory cusps that are sporadically present in the P3s of other species are absent in SCT 19. D. samniticus sp. nov. differs from D. masinii by having an imperfectly defined parastyle.

P4 bears a low protocone, like in Deinogalerix masinii and D. freudenthali from F15. In contrast, D. brevirostris , D. intermedius , and D. koenigswaldi have a quite higher protocone. The hypocone is comparatively as high as it is in smaller species, and quite lower than those of D. brevirostris , D. intermedius , and D. koenigswaldi . It is not split. In the other species the hypocone can be either complete, or variably split. It is quite more split in D. koenigswaldi . The tooth bears no accessory cusps.

In M3 of Deinogalerix samniticus sp. nov. the parastyle is somewhat more developed than in the other species, giving the labial wall a slightly concave profile. The parastyle is projected mesio-labially as in the small species D. masinii and D. freudenthali from F15 and not mesially as in D. koenigswaldi and the F 9 specimens. Moreover, the angle between the mesial and labial margins is acute in D. samniticus sp. nov., D. freudenthali from F15, and D. masinii , and more open in D. brevirostris , D. koenigswaldi , and in a still undetermined species, Deinogalerix sp. from F9.

Figures

FIGURE 5. Deinogalerix samniticus sp. nov., from Scontrone. 1–2, Holotype, fragment of left hemimandible, with p3, p4, alveoli of p2, broken m1, m2, and m3 partially embedded in the rock (SCT 246). 1, labial view; 2, occlusal view. 3– 5, Paratype, isolated left m1 (SCT 347). 3, occlusal view; 4, labial view; 5, lingual view. 6–7, Paratype, fragmental right maxillary with complete P3 and fragmented P4 (SCT 19). 6, occlusal view; 7, lingual view. 8, Paratype, fragmental right maxillary, with M3 and postero-lingual portion of M2 (SCT 232).

FIGURE 7. Comparisons of p3–m3 lengths in the different species of Deinogalerix, as well as in Parasorex, Galerix, Schizogalerix, and Apulogalerix (measurements and abbreviations in Table 3). 1, The graph shows that in Apulogalerix, Parasorex and other continental galericines molars grow progressively larger towards m1, which is the largest tooth of the row. The fourth lower premolar is larger than p3, which, in contrast, is the smallest of the toothrow (it is somewhat smaller than m3). Compared to the mainland counterparts, Deinogalerix bears a very large m1 (due to the increase of the trigonid length) and larger premolars, that grow progressively smaller moving rostrally, but less than in the continental genera (p3 intermediate in size between m1 and m2). The Scontrone specimen shows the size increase from m3 to m1 typical of Deinogalerix. In contrast, it bears a very large p4, similar in size to m1 and in the dimensional ranges of D. koenigswaldi, and a very reduced p3, more similar to those of the smaller and more primitive species of Deinogalerix from Gargano. 2, Ratio diagram comparing the p3–m3 lengths (see Table 4) in Deinogalerix samniticus sp. nov. with other species of Deinogalerix, using Parasorex socialis from La Grive as the standard (horizontal line). All the Deinogalerix specimens show a similar trend where the proportions of m2 and m3 are parallel to the standard, whereas, starting from m1, the teeth proportionally increase in size respect to the standard. It is noteworthy that this trend reaches its maximum expression in D. koenigswaldi. Compared to the other species of Deinogalerix, the curve of D. samniticus sp. nov., shows a steeper rise toward p4, and it is the only one that drops toward p3.

FIGURE 8. Scatter plot of Lp4 vs Lp3 (values in Table 5) for the species of Deinogalerix. The Deinogalerix specimens from Gargano align roughly in a linear trend. D. samniticus sp. nov. and Deinogalerix sp., in contrast, display an anomalously short p3. It is worth noting that also the smaller and more primitive species, e.g., D. freudenthali from F15 and D. masinii from M013, have fairly short p3s. Measurements in mm.

FIGURE 6. 1–3, Holotype SCT 246 during its preparation from the rock matrix by vibrotool. The figure shows the pre- molars still partially encased in the rock matrix.

FIGURE 4. 1, Left M1 (F9-018), undetermined Deinogalerix sp. from fissure F9, oblique, occluso-distal view. 2, same as 1 with sketch showing contact of the distal arm of the metaconule with the uninterrupted distal cingulum. 3, left m1 (paratype SCT 347), Deinogalerix samniticus sp. nov., occlusal view. 4, same specimen as 3, lingual view. Arrows in 3 and 4 showing mesiolingual bulge. 5, left p4 (holotype SCT 246), Deinogalerix samniticus sp. nov., occlusal view. 6, same as 5, with sketch showing roundish, delimited lingually, trigonid valley. 7, right P3-P4 (paratype SCT 19), Deinogalerix samniticus sp. nov., occlusal view. 8, same as 7 with sketch showing the weak separation of protocone and hypocone. Hyc = Hypocone, Mecl = Metaconule, Mec = Metacone, Mecd = Metaconid, Pac = Paracone, Pacd = Paraconid, Prc = Protocone, Prcd = Protoconid. Figures not to scale.