Fibularia damensis Kier, new species
59 : figures 2-10 ;
Plate 60 :
Echinocyamus sp., Steineke, Bramkamp,
Sander, 1958: 1313.—Powers, Ramirez, Redmond, and Elberg 1966: D92,
093, D95, D97
DIAGNOSIS. — Species
characterized by well-developed petals and low test with height equal
to 54.6 percent of the length of the test.
MATERIAL. — Hundreds of
specimens but description based on 38 specimens from one locality.
SHAPE. — Test 4.5-10.0 mm
long with mean of 7.1 mm, greatest width at apical system or anterior,
width 86.6 percent L (S.D. 3.5, C.V. 4.1, N-37) ; greatest height
anterior to apical system, height 54.6 percent L (S.D. 4.9, C.V. 8.9,
N-38) ; adapical surface flat or slightly inflated, petals flush on
some specimens, slightly inflated on others, apical system slightly
inflated; marginal outline oblong on most smaller specimens,
subpentagonal on larger with anterior pointed; periproct flush,
peristome slightly depressed only along immediate edge of opening;
adorai surface slightly depressed to slightly convex.
APICAL SYSTEM. — Central
to slightly anterior, distance from anterior margin of test to
anterior genital pores 46.7 percent L (S.D. 2.3, C.V. 4.8, N-37) ;
width of apical system as measured across posterior genital pores 7.3
percent L (S.D. 1.3, C.V. 17.6, N-37) ; four genital pores arranged in
trapezoid with anterior pair doser together; hydropore in furrow
(Plate 59: figure 2).
— Petals long and broad, extending almost to margin, of approximately
equal length; length of petal III 40.6 percent L (S.D. 2.9, C.V. 7.2,
N-38), width 18.6 percent L (S.D. 1.9, C.V. 10.6, N-37) ; greatest
width of petals near midlength or slightly distal; interporiferous
zones expanding distally (Plate 59: figure 2), poriferous zones
narrowing distally; pores conjugate (conjugation grooves visible only
on well-preserved specimens), opening circular; smallest specimen 4.5
mm long with 8 porepairs in single poriferous zone in petal 1, 6 in
petals II and III, largest specimen 9.8 mm long with 12 in petal I,
eleven in petals II, III; average of 8.8. porepairs in ail measured
specimens in petal I, 7.1 in II, 8.5 in III with mean of 1.2 porepairs
in single poriferous zone for each millimeter of length of test in
petal I, 1.0 in petal II, 1.2 in petal III.
PERISTOME. - Central,
subcircular to subpentagonal, slightly higher than wide (Plate 59:
figure 4), height 13.5 percent L (S.D. 1.6, C.V. 12.1, N-38).
PERIPROCT. - Situated
nearer peristome than posterior margin, at distance from peristome
equal to 9.7 percent L (S.D. 1.6, C.V. 16.5, N-38) ; oblong, height
greater than width, opening smaller than peristome.
INTERNAL STRUCTURES. - No
internal structure (Plate 60: figure 1) ; auricles interradial.
COMPARISON WITH OTHER
SPECIES. - This species is easily distinguished from most species of
Fibularia by its well-developed petals. It is most similar to
Fibularia dubarensis Kier from the Miocene of British Somaliland
in having similarly shaped petals, and my first impression was that
the Arabian specimens belonged to this species. When I described the
Somali-land species I did not make an adequate number of measurements
and therefore could not make a definitive comparison of the Arabian
and Somaliland specimens. I borrowed from the Sedgwick Museum 86
specimen and have now made the necessary measurements, the
compilation of which follows this paragraph. The Arabian species is
distinguished from the Somaliland F. dubarensis by its lower test with
a height equal to 54.6 percent the length as opposed to 65.8 percent
in F. dubarensis. A student t-test shows that the chances are
far less than one in a thousand that the specimens came from one
The following are the
statistics of 70 specimens of Fibularia dubarensis Kier, 1957:870,
from the Miocene of British Somaliland. These specimens are in the
Sedgwick Museum, Cambridge, England.
Length: mean 8.1 mm (S.D. 2.2, C.V. 28.3, N-70).
Percent width of L: 87.9 (S.D. 3.1, C.V. 3.5, N-70) . Percent height
of L: 65.8 (S.D. 5.8, C.V. 8.7, N-70). Percent length of petal III of
L: 45.6 (N-60).
Percent width of petal III of L: 18.5 (S.D. 2.1,
C.V. 11.7, N-63).
Percent width of apical system of L: 7.4 (S.D. 1.1,
C.V. 15.4, N-66).
Percent distance from apical system to anterior
margin of L: 47.5 (S.D. 3.1, C.V. 6.5, N-68).
Percent height of peristome of L: 12.8 (S.D. 1.8,
C.V. 14.3, N-61).
Percent height of periproct of L: 10.5 (S.D. 1.2,
C.V. 11.5, N-62).
Percent distance from periproct to peristome of L:
9.0 (S.D. 2.3, C.V. 19.6, N-63) .
Ratio of number of porepairs in single poriferous
zone to length of test in millimeters.
Petal I: 1.4
Petal II: 1.2
Petal III: 1.5
in general appearance resembles Echinocyamus woodi Currie
(1930:172) from the Miocene of British East Africa. Dr. Currie does
not state whether her species has internai partitions which would be
expected if it was an Echinocyamus. F. damensis differs
in having fewer porepairs in its petals. Her figured specimen of E.
woodi which is 8.4 mm long has 12-13 porepairs in each poriferous
zone, whereas a specimen of similar size of F. damensis has
TYPE SPECIMENS. -
Holotype, USNM 170481; figured paratypes, 170482-170484.
AND LOCALITIES. ‑ Miocene, Dam Formation, localities S-137, S-178,
S-553, S-568, S-1392.
59 & 60