Gnathostomulida from the Otago Peninsula, southern New Zealand
Author
Sterrer, Wolfgang
text
Zootaxa
2006
2006-04-13
1172
1
19
journal article
27070
10.5281/zenodo.2645647
e1ec4acf-3db4-4cd9-97fa-5645a0685e5b
1175-5326
2645647
321024B7-8CE2-45F0-B683-70D600C2215A
Pterognathia ugera
Sterrer, 1991
(Fig.Fig. 4.4–4.6)
Material
Four juveniles/anterior fragments from sample SI 16.
Distribution
Tahiti (
Sterrer 1991c
), (sub)tropical NW Atlantic (
Sterrer 1998
).
Description
Rostrum measurements of this colorlessopaque species were
175–270 µm
in length and
45–50 µm
in width (index 4.64). The pharynx is
12.67 µm
long behind the symphysis. The basal plate,
7.75 µm
long and
11.25 µm
wide (index 0.70) is horseshoeshaped, bearing a pair of laterocaudally pointing wings; its rostral rim is entirely set with 25–31 (28.00) very regular teeth. The jaws are compact,
13.75 µm
long, with short rostral apophyses and 3–4 teeth. In unsqueezed specimens the basal plate covers the jaws such that the jaw apophyses coincide with the laterocaudal extensions of the basal plate (Fig. 4.5).
TABLE 6.
Morphometric data for
Pterognathia ugera
.
| Mean |
SD |
Max |
Min |
n |
| Body length of adults |
1750.00 |
1 |
| Body width of adults |
30.00 |
1 |
| Body index of adults |
58.33 |
1 |
| Rostrum index of adults |
5.17 |
1 |
| Jaw length |
18.00 |
0.00 |
18 |
18 |
5 |
| Basal plate length |
4.20 |
0.84 |
5 |
3 |
5 |
| Basal plate width |
10.40 |
0.55 |
11 |
10 |
5 |
| Basal plate index |
0.41 |
0.09 |
0.50 |
0.27 |
5 |
| Sperm length |
32.00 |
1 |
| Sperm width |
1.00 |
1 |
| Sperm index |
32.00 |
1 |
Discussion
Easily identified by its unique basal plate, this circumtropical species may eventually warrant a separate genus due to its distinctive mouth part architecture (
Sterrer 1998
).
FIGURE 4.
Pterognathia
spp. 4.1–4.3
Pterognathia sica
,
basal plate and jaws of two specimens (4.1 is a drawing of the preserved wholemount of 4.2); 4.4–4.6
Pterognathia ugera
,
basal plate and jaws of three specimens (4.5 is a ventral view, unsqueezed); 4.7–4.8
Pterognathia portobello
nov. spec.
, basal plate and jaws of holotype (4.7 less squeezed than 4.8). All to the same scale as Fig. 1.
Pterognathia portobello
n. sp.
(Fig.4.7–4.8)
Type material
Holotype
one anterior fragment from sample SI 16, in squeeze preparation,
NZNM
W.1535.
Etymology
In appreciation of facilities and help provided during my stay at the Portobello Marine Laboratory, University of
Otago
, Dunedin,
New Zealand
.
Diagnosis
Pterognathia
with delicate jaws
13 µm
long. Basal plate
2 µm
long and
14 µm
wide (index 0.14), with several rows of many minute teeth over median two thirds of rostral edge.
Description
The only specimen, an anterior fragment, was colorlesstranslucent,
1350 µm
long and
50 µm
wide, and had a rostrum
270 µm
long and
35 µm
wide (index 7.71).
The basal plate is a thin transverse sliver,
2 µm
long and
14 µm
wide (index 0.14), with pointed lateral tips. The median two thirds of its rostral edge are set with two or more horizontal rows of minute thornlike teeth. The jaws are
13 µm
long and delicate. The narrow symphysis lamellae join posteriorly in a small, globular symphysis. Anteriorly the jaws broaden, but it was not possible to identify distinct features such as rostral apophyses or cristae. Each jaw terminates dorsorostrally in a knob, and ventrorostrally seemed to have 4–5 teeth. The pharynx measures
10 µm
in length behind the symphysis.
Nothing is known about the reproductive system.
Discussion
A muchwiderthanlong basal plate and manytoothed jaws characterize
Cosmognathia
and
Pterognathia
. In its ‘frontheavy’ jaw architecture the new species most resembles
Pterognathia ugera
Sterrer, 1991
. Although the single specimen represents without doubt a new species, the fragmentary and delicate nature of its features suggests leaving the assignment to genus tentative pending an analysis of additional material.