Conchocele pangasinanensis, Kiel & Fernando & Magtoto & Kase, 2022
|
publication ID |
https://doi.org/ 10.4202/app.00977.2022 |
|
persistent identifier |
https://treatment.plazi.org/id/0470A855-EA7E-FF90-FF66-F90F8A20F963 |
|
treatment provided by |
Felipe |
|
scientific name |
Conchocele pangasinanensis |
| status |
sp. nov. |
Conchocele pangasinanensis View in CoL sp. nov.
Fig. 6A–D View Fig .
Zoobank LCID: urn:lsid:zoobank.org:act:157EFA74-F306-45B6-AE7B-CDB71E19469B
Etymology: For the province of Pangasinan, where the Northern Cement Corporation Quarry is located.
Type material: Holotype NIGSPAL-009, isolated RV with preserved hinge; paratype NIGSPAL-011 from the type locality and horizon.
Type locality: The “shale quarry” within the Northern Cement Corporation quarry in Pangasinan province, Luzon, Philippines .
Type horizon: Seep carbonate blocks enclosed in the Amlang Formation (Upper Miocene) .
Material.— 20 specimens from block B (NIGSPAL-010, 034, NRM Mo 192566–192582, 192588) , one specimen from block D (NIGSPAL-035), 2 specimens from block F ( NRM Mo 192544–192545) , 19 specimens from block G (NIGSPAL-009, NRM Mo 192685–192702), and 4 specimens from the NCC collection (NIGSPAL-036, 037 [3 specimens on one sample]). All from the type locality and horizon .
Dimensions ( in mm).— Holotype (NIGSPAL-009): L = 66.0, H = 64.4, W (single) = 22.0; NRM Mo 192544: L = 59.0, H = 59.0, W = 34.4; NRM Mo 192588: L = 61.3, H = 54.5, W = 37.8; paratype (NIGSPAL-011): L = 76.6, H = 63.0, W (single) = 19.7; NIGSPAL-036: L = 77.0+, H = 63.5+, W (single) = 19.7; NIGSPAL-037: L = 68.0, H = 67.2, W (single) = 21.5.
Diagnosis.—Moderate size for genus, well-inflated, outline rounded-quadrate, sharp posterior ridge with wide posterodorsal area, secondary posterior grove present but indistinct, umbones blunt, strongly prosogyrate.
Description.—Moderately sized, well-inflated shells, W/H ratio 0.58–0.69, rounded-quadrate outline, umbones terminal, blunt, prosogyrate; anterior margin long, concave; anterodorsal area broad, with indistinct internal ridge and groove, bordered by blunt ridge; posterodorsal area wide, bordered by deep sulcus and sharp ridge that form deep indentation at posterior margin, secondary ridge indistinct; ventral margin broadly convex, with slight angulation in some specimens, ending posteriorly at posterior sulcus; outer surface with fine, irregular growth lines. Anterior adductor muscle scar narrow, elongate, detached from, and parallel to, pallial line, length about 2/5 th of shell length.
Remarks.—Numerous species- and subspecies-level names exist for large, Neogene thyasirids from the western Pacific region, and many specimens have simply been reported as Conchocele bisecta ( Conrad, 1849) or C. disjuncta Gabb, 1866 ( Yabe and Nomura 1925; Krishtofovich 1936, 1964; Squires and Gring 1996; Majima et al. 2005; Hryniewicz et al. 2017). A revision of these names and taxa is pending. Virtually all of these species, however, differ from Conchocele pangasinanensis by being more elongate. Species with more rounded-quadrate shape as Conchocele pangasinanensis include Conchocele majimai Kiel, Aguilar, and Kase, 2020a , and Conchocele visayaensis Kiel, Aguilar, and Kase, 2020a , two Plio-Pleistocene species from seep deposits in Leyte of the Philippine islands ( Kiel et al. 2020a). Conchocele pangasinanensis differs from those two species by its broader umbonal angle (angle between antero- and posterodorsal margins) and its posterodorsal ridge and sulcus do not slope downward as much as in the two species from Leyte. Conchocele adoccasa Van Winkle, 1919 , from the Middle Miocene of Trinidad and possibly Oligocene seep deposits of Colombia is flatter and has a narrower posterodorsal area than Conchocele pangasinanensis ( Van Winkle 1919; Gill et al. 2005; Kiel and Hansen 2015).
Stratigraphic and geographic range. —Upper Miocene of Luzon, Philippines.
Conchocele aff. quadrata ( Yabe and Nomura, 1925) Fig. 6E View Fig .
Material.— One specimen from the NCC collection (NIGSPAL-012, L = 66.0 mm, H = 62.7 mm, W [single] = 21.8 mm). Upper Miocene of the “shale quarry” within the Northern Cement Corporation quarry in Pangasinan province, Luzon, Philippines .
Remarks.—In overall shape, inflation and especially the narrow posterodorsal area, this specimen resembles Conchocele quadrata Yabe and Nomura, 1925 , from an unknown locality in Japan ( Yabe and Nomura 1925: pl. 1: 1) though it differs from the Japanese specimen by its slightly less truncate posterior margin and the more convex ventral margin. A specimen illustrated as C. quadrata from the Upper Miocene of Sakhalin Island in eastern Russia ( Krishtofovich 1964: pl. 53: 1) is more quadrate and has a wider posterodorsal area than both the Japanese and the Philippine specimens.
Family Lucinidae Fleming, 1828 View in CoL
Genus Megaxinus Brugnone, 1880 View in CoL
Type species: Lucina transversa Bronn, 1831 , subsequent designation by Pallary (1904), see Glover and Taylor (1997) for a detailed discussion; Pliocene, Italy.
Megaxinus gorrospei sp. nov.
Fig. 7 View Fig .
Zoobank LCID: urn:lsid:zoobank.org:act:768EE30D-DE0E-4B20-B6DF-D90B9B0FCC74
Etymology: For Oliver R. Gorrospe, Vice President and General Manager of the Northern Cement Corporation, who aided collections within the quarry.
Type material: Holotype NIGSPAL-015, articulated specimen with most shell material preserved; paratypes: NIGSPAL-013, 014, 016 (all from block A) and NRM Mo 192433 (from block E), small, isolated LV. All from the type locality and horizon.
Type locality: The “shale quarry” within the Northern Cement Corporation quarry in Pangasinan province, Luzon, Philippines .
Type horizon: Seep carbonate blocks enclosed in the Amlang Formation (Upper Miocene) .
Material.— Type material only.
Dimensions ( in mm).— Holotype (NIGSPAL-015): L = 31.4, H = 35.1, W = 18.1; paratypes: NIGSPAL-013: L = 31.6, H = 28.2, W = 15.5; NIGSPAL-016: L = 38.3, H = 37.2, W = 22.5; NRM Mo 192433: L = 27.8, H = 25.4.
Diagnosis.—Subquadrate to broadly triangular, moderately inflated shell; anterodorsal shell margin straight; no lunule; hinge plate short, moderately broad, edentulous; blunt posterior ridge close to dorsal shell margin, posterodorsal area narrow; anterior adductor muscle scar narrow, elongate, length 2/5 of shell length, close to pallial line.
Description.—Shell of medium size for genus, ontogenetic change in shell shape from subquadrate in smaller specimens to broadly triangular in adults. Posterior ridge more pronounced in adults, close to dorsal margin, corresponding posterodorsal area narrow; surface sculpture of commarginal growth lines only: umbones elevated above hinge line, pointed, prosogyrate; posterodorsal and ventral shell margins convex, anterodorsoal margin nearly straight. Lunule large, elongate. Anterior adductor muscle scar elongate, narrow, close and parallel to ventral shell margin, length about 2/5 of shell length; posterior adductor muscle scar just above mid-height of shell, diamond-shaped; pallial line entire, very close to ventral shell margin. Hinge plate broad, short, edentulous, with weak central undulation.
Remarks.—Species of Megaxinus show an ontogenetic change in shell shape, from being circular when small, whereas larger shells are higher with a more quadrate anterior (Glover and Taylor 1997: 8). Megaxinus gorrospei sp. nov. resembles those more angular, large species of Megaxinus , and is hence placed in this genus. The extant genus Rasta Taylor and Glover, 2000 , includes shells with very similar shell outline and hinge (Taylor and Glover 1997, 2000; Glover and Taylor 1997; Taylor et al. 2005), but Rasta species are much less inflated than Megaxinus gorrospei and smaller.
Externally, shells of Megaxinus gorrospei are very similar to large specimens of Megaxinus ellipticus ( Borson, 1825) from the Pliocene of Italy ( Kiel and Taviani 2018), and its anterior adductor muscle scar (aams) is very close to the pallial line, as in Megaxinus ellipticus as illustrated by Sacco (1901: pl. 17: 13) and M. stironensis Kiel and Taviani, 2018 . In most extant species of Megaxinus illustrated by Glover and Taylor (1997), however, the aams appears to deviate from the pallial line at a somewhat larger angle, especially at its ventral end, than in the Miocene Philippine Megaxinus gorrospei . Most extant species of Megaxinus have a bulge or convexity in the anterodorsal shell margin (Glover and Taylor 1997), absent in Megaxinus gorrospei .
Megaxinus gorrospei differs from Megaxinus ellipticus by its longer and more acutely rounded posterior part of the shell, lacking a distinct lunule, and its narrower hinge plate. The Pliocene Megaxinus stironensis from Italy has a more roundish outline than Megaxinus gorrospei , even at large size, and unlike Megaxinus gorrospei , it bears a lunule ( Kiel and Taviani 2018).
Stratigraphic and geographic range. —Upper Miocene of Luzon, Philippines.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
|
Kingdom |
|
|
Phylum |
|
|
Class |
|
|
Order |
|
|
Family |
|
|
Genus |
Conchocele pangasinanensis
| Kiel, Steffen, Fernando, Allan Gil S., Magtoto, Clarence Y. & Kase, Tomoki 2022 |
Megaxinus
| Brugnone 1880 |
Lucinidae
| Fleming 1828 |