Masticacheles longirostris, Fraaije & Krzemiński & Van Bakel & Krzemińska & Jagt, 2014
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publication ID |
https://doi.org/ 10.4202/app.2012.0022 |
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persistent identifier |
https://treatment.plazi.org/id/03C29868-902B-FFCD-FFEC-396AFDB21337 |
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treatment provided by |
Felipe |
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scientific name |
Masticacheles longirostris |
| status |
sp. nov. |
Masticacheles longirostris sp. nov.
Figs. 2D–F View Fig , 3B View Fig .
Etymology: In reference to the distinct rostrum. Type material: Holotype is I−F/MP/6194/1577/10(ISEA), a near−complete shield (maximum length 3.0 mm, maximum width 2.5 mm), from Ogrodzieniec; paratypes are I−F/MP/3958/1533/08 (ISEA), a near−complete shield (maximum length 3.5 mm, maximum width 3.0 mm), from Bzów, and MAB k. 3204, a near−complete shield (maximum length 4.0 mm, maximum width 3.5 mm), from the same locality.
Type locality: Large abandoned quarry at Ogrodzieniec, southern Poland .
Type horizon: On ammonite evidence, the section exposed at Ogrodzieniec can be dated as early to middle Oxfordian. With the exception of the discontinuous Quenstedtoceras mariae Zone , all zones and subzones from the Cardioceras cordatum to the Gregoriceras transversarium zones, have been documented ( Głowniak 2006). The specimens most probably originated from the upper levels exposed at this locality.
Diagnosis.—As for the genus, by monotypy.
Description.—Well−calcified and clearly areolated shield, slightly longer than wide, strongly convex transversely, slightly convex longitudinally. Pronounced, slightly downturned, triangular rostrum, with a broad median ridge that extends towards the gastric region into a smaller central gastric groove. Orbital cavities rimmed and subcircular, bounded by triangular, forwardly directed, post−ocular spines. Ocular−frontal area equalling about 60% of maximum shield width. Antennal area bordered by elevated, elongated ridge. Posteriorly pointed, bluntly arrowhead−shaped to obtuse gastric region, bounded laterally by massetic grooves, posteriorly by deep V−shaped cervical groove; anterior part covered by transverse crenulations. Mesogastric process absent. Prominent, globose and rhomboidal anterior massetic region forming widest part of shield. Posterior massetic region of more or less equal size, but more elongated transversely. Both anterior and posterior massetic regions wider than long. V−shaped cervical groove pronounced and very deep, especially around the keraial region were the cervical groove has a typical crook on both sides. Lateral of the keraial region the major portion of an elongated anterior branchial area is present. Cardiac region or other more posterior parts are not preserved.
Remarks.— Masticacheles longirostris gen. et sp. nov. is yet another new member of the Parapylochelidae . Prior to this study only two species were known: Mesoparapylocheles michaeljacksoni Fraaije, Klompmaker, and Artal, 2012a (mid−Cretaceous; Navarra, northern Spain) and Parapylocheles scorpio (extant; Indo−Pacific Ocean, between 200 and 1,000 m; compare Forest 1987a). The new taxon can be distinguished by having a ridged rostrum, rimmed orbital cavities, more or less equal−sized massetic regions and a much less angular cervical groove. Masticacheles longirostris sp. nov. and Mesoparapylocheles michaeljacksoni are found, without any clue as to their ethology, in deposits laid down in relatively shallow−water, reefal settings, whereas P. scorpio is xylicolous, preferring mainly hollow pieces of bamboo, in relatively deep−marine environments. Thus, based on current data, parapylochelids appear to have migrated into deeper waters during the course of their evolution. The absence of suitable and transportable straight, hollow and firm shelters in Upper Jurassic and mid−Cretaceous sediments from which the material described originates (e.g., no dentaliid molluscs, serpulid tubes or wood fragments), allows to conclude that parapylochelids changed their ethology also, possibly preferring a mutualistic lifestyle with sponges. Several types of sponges are common in Mesozoic reefs. Such a mutualistic lifestyle, with hexactinellids and demosponges, is known for modern pylochelids ( Forest 1987a).
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