Necronectes michelini
Creators: name: Ossó, Àlex
name: Gagnaison, Cyril
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Portunidae
Necronectes
Necronectes michelini

description: Necronectes michelini (A. Milne-Edwards, 1861)(Fig. 5 D-F)
Scylla michelini A. Milne-Edwards, 1861: 137, pl.3., figs 3-3A. — Couffon 1908: 3, 4, pl. 1, figs 6-10, pl. 2, figs 1, 2. — Schweitzer et al. 2006: 122; 2010: 110. — Karasawa et al. 2008: 106. — Emmerson 2017: 584.
Cancer macrochelus – Millet 1854: 152 (non Desmarest, 1817).
Scylla cf. michelini – Glaessner 1928: 184, 185.
Scylla? michelini – Glaessner 1929: 374.
Scylla sp. (cf. michelini) – Lőrenthey & Beurlen 1929: 178, pl. 15, figs 5, 6.
Necronectes michelini – Glaessner 1933: 5-6. — De Angeli & Marangon 1992: 178, 179.
Scylla michelini? – Betancort et al. 2014: 345, pl. 1, figs K1-K2 (non I1-I2)
MATERIAL EXAMINED AND MEASUREMENTS (in mm). — Two dactyli. Right dactylus, ULB-SO-9: L = 41.38, H = 25. — Left dactylus (tip broken off), ULB-SO-10: L = 32.53, H = 15.52.
LOCALITY AND HORIZON. — ‘La Sonneterie’ quarry, Meigné-le- Vicomte (Maine-et-Loire). ‘Savignean facies’, Langhian-Serravallian (Middle Miocene).
DESCRIPTION
Right dactylus stout, gently curved forward; subrectangular in section with rounded upper angles; strong proximal knobstick molariform tooth followed by six serial rounded conical teeth of different sizes; rounded tip. Left dactylus stout, gently curved forward; subrectangular in section with rounded upper angles, proximal tooth and tip not preserved.
REMARKS
Scylla michelini was erected based on fragmentary chelipeds and was referred to Scylla De Haan, 1833, because of its similarity to the strong chelipeds of the extant S. serrata (Forskål, 1775). Nevertheless, A. Milne-Edwards (1861: 136), pointed out the absence in S. michelini of the two typical distinct spines on the distal upper part of the palm, near the insertion of dactylus (see Couffon 1908: pl. 1, figs 6-10, t. 2, figs 1, 2; MNHN.F.B25950, which are present in Scylla species (e.g. Keenan et al. 1998; Trivedi & Vachhrajani 2013). Rathbun (1918: 168), when described Necronectes proavitus (as Gatunia proavita), pointed out as well, the absence of those spines as a differential trait with Scylla, and also noted the striking similarity between the cheliped of N. proavitus and that of S. michelini (Rathbun 1918: 171). Furthermore, A. Milne-Edwards (1861: 136) noted as well, that the upper margin of the palm of S. michelini is rounded, whereas it is usually more flattened and angled in Scylla species (see Keenan et al. 1998: fig. 8).
Subsequently, several authors assigned similar fragmentary remains of dactyli y to Scylla michelini (see synonym list). Glaessner (1933: 5), included S. michelini within Necronectes A. Milne-Edwards, 1881, being followed by De Angeli & Marangon (1992: 178, 179). Nevertheless, this placement was questioned by Schweitzer et al. (2006: 121, 122), which retained S. michelini within Necronectes (see also Karasawa et al. 2008: 106).
The aforementioned differences in the palms, such as the absence of the outer and inner spines on distal margin, and the strong spine at carpal articulation of propodus, further, the absence of spines on the outer part of carpus, peculiar of the most species of Scylla possesses (e.g. Keenan et al. 1998: fig. 8; Trivedi & Vachhrajani 2013: fig. 5a-c), allow us to confirm the generic placement of S. michelini within Necronectes, as it was previously placed by Glaessner (1928, 1933).
description: Published as part of Ossó, Àlex & Gagnaison, Cyril, 2019, An appraisal of the Middle-Late Miocene fossil decapod crustaceans of the ' Faluns' (Anjou-Touraine, France), pp. 367-383 in Geodiversitas 41 (9) on pages 376-377, DOI: 10.5252/geodiversitas2019v41a9, http://zenodo.org/record/3700034