Laeviprosopon lanceatum, Starzyk & Van Bakel & Klompmaker & Schweigert & Fraaije, 2023
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publication ID |
https://doi.org/ 10.26879/1204 |
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publication LSID |
lsid:zoobank.org:pub:C7630846-28CE-4F22-90FE-F970ACE300BA |
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persistent identifier |
https://treatment.plazi.org/id/DA645246-FF9D-FFB2-FC60-EF3FF04FF96A |
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treatment provided by |
Felipe |
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scientific name |
Laeviprosopon lanceatum |
| status |
sp. nov. |
Laeviprosopon lanceatum n. sp.
Figures 1 View FIGURE 1 , 8 View FIGURE 8
zoobank.org/ 4A54E1D0-43A6-4786-A202-005D820F9D4D
Diagnosis. Carapace longer than wide. Rostrum with a very long central spine. Orbital margin round, surface posterior to orbits convex. Epigastric regions strongly vaulted. Large tubercle on each hepatic region. Epigastric, protogastric and hepatic regions separated by transverse grooves.
Etymology. The name lanceatum derives from the Latin word “lancea” – spear. It refers to the prominent rostrum.
Comparisons. The holotype of Laeviprosopon lanceatum n. sp. is much smaller than specimens of L. laeve , but there is not enough material to ascertain whether the small size is a true character of this species or the specimens are just juveniles. Its carapace is widest on the hepatic region, as in most species of the genus except L. joecollinsi n. sp., L. musialiki , L. lazarae and L. ewakrzeminskae n. sp. The carapace is elongated unlike in L. planum , L. crassum and L. hispanicum . The anterior and posterior part of the mesogastric region of L. lanceatum n. sp. is more or less the same length unlike in L. musialiki , L. laeve , L. lazarae , L. sublaeve , L. grandicentrum , L. laculatum , L. fraasi , L. planum , L. hispanicum and L. crassum . Symmetrical tubercles on the mesogastric region present in L. laeve are absent in L. lanceatum n. sp. A single large tubercle on each side of the posterior part of the mesogastric region present in L. lanceatum n. sp. is also present only in L. lazarae and L. grandicentrum . Epigastric, protogastric and hepatic regions are separated by transverse grooves as in L. laeve , L. joecollinsi , L. lazarae , L. sublaeve , L. ewakrzeminskae n. sp. and L. fraasi . Epigastric regions are rounded in L. lanceatum n. sp., not short and wide as in L. lazarae and L. sublaeve . Laeviprosopon lanceatum n. sp. has a rostrum with a very long central spine not noticed in any other species of the genus.
Material Examined
Type material. Holotype: I-F/ MP/736 /1502/08; type locality: Ogrodzieniec; age: early–middle Oxfordian.
Paratype. I-F/ MP/342 /1497/08; locality: Niegowonice; age: middle – late Oxfordian (upper elizabethae Subzone – upper wartae Subzone) .
Dimensions. Specimens are not well preserved, and thus most measurements cannot be taken accurately. Length of the mesogastric region of the holotype is 0.9 mm, of the paratype 1.4 mm. Carapace width at the level of the hepatic region is 1.4 mm for the holotype and 1.6 mm for the paratype.
Description. The carapace is longer than wide, widest on the hepatic region, strongly vaulted transversally and moderately vaulted longitudinally ( Figure 8 View FIGURE 8 A-B, F). The anterior part of the carapace in front of the cervical groove is relatively long.
The rostrum is only preserved as an impression with a very long central spine preserved in both specimens. The base of rostrum is very wide, and the central spine is located between damaged bases of the lateral parts of rostrum ( Figure 8C, D, E, F View FIGURE 8 ). The orbital margin is rounded. There is a groove separating the base of the rostrum and the orbital margin. The surface behind the orbits is slightly convex ( Figure 8A, C, E View FIGURE 8 ).
The epigastric regions are rounded, strongly vaulted, partially preserved on both specimens. The mesogastric region is distinctly bounded by grooves. The anterior (narrow) and posterior (wide) part of this region are more or less the same length. The posterior part is the highest point of the carapace. There is no incision between the anterior and posterior part of this region ( Figure 8 View FIGURE 8 ).
A pair of small, rounded gastric pits is present in the cervical groove. There is a pair of large hepatic tubercles on both sides of the posterior part of the mesogastric region (one on each side) ( Figure 8 View FIGURE 8 A-B, D, G). The epigastric, protogastric and hepatic regions are separated by transverse grooves ( Figure 8A View FIGURE 8 ).
The urogastric region is convex and relatively broad, delimited by the postcervical groove. There are very narrow grooves laying parallel to the lateral parts of the branchiocardiac groove ( Figure 8A View FIGURE 8 ). The cardiac region is not distinctly bordered, narrowing posteriorly, with two tubercles in the posterior part.
The grooves are very wide and deep. The cervical groove is the deepest. The internal mold of the carapace is covered with small tubercles. The cuticle is not preserved.
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