New calmoniid trilobites (Phacopina, Acastoidea) from the Devonian of Bolivia

18 Pages·2003·3.4 MB·English

by  Carvalho, Maria da Gloria Pires de

AMERICAN MUSEUM
Novitates
PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3407, 17 pp., 6 figures May 22, 2003
New Calmoniid Trilobites (Phacopina: Acastoidea)
from the Devonian of Bolivia
MARIA DA GLORIA PIRES DE CARVALHO,! GREGORY D. EDGECOMBE,’
AND LEGRAND SMITH?
ABSTRACT
Four new taxa of Lower Devonian Calmoniidae from Bolivia are described: Gemelloides
delasernai, n. gen. and sp., Eldredgeia eocryphaeus, n. sp., Wolfartaspis liebermani, n.
sp., and Granadocephalus hannibali, n. gen. and sp. The new genus Gemelloides is sister
taxon to Vogesina Wolfart, 1968. Eldredgeia eocryphaeus, from the Scaphiocoelia Assem-
blage Zone in La Paz and Tarija Departments, closes a stratigraphic gap/ghost lineage in
the early history of the Metacryphaeus group. Wolfartasapis liebermani (Icla Formation,
Kochis, central Bolivia) predates its only congener, W. cornutus. A novel combination of
features within Calmoniidae characterizes Granadocephalus hannibali, from the Icla For-
mation in Cochabamba Department. This monotypic genus may have its closest relatives
in the Calmonia group.
RESUMEN
Se describen cuatro nuevos taxa de la familia Calmoniidae del Dev6énico Boliviano:
Gemelloides delasernai, n. gen. y sp., Eldredgeia eocryphaeus, n. sp., Wolfartaspis lie-
bermani, n.sp., y Granadocephalus hannibali, n.gen. y sp. El nuevo género Gemelloides
es el grupo hermano de Vogesina Wolfart 1968. Eldredgeia eocryphaeus, registrada para
la fauna de la biozona Scaphiocoelia en los departamentos de La Paz y Tarija, cierra un
‘Research Associate, Division of Paleontology, American Museum of Natural History. e-mail: [email protected]
? Principal Research Scientist, Australian Museum, 6 College Street, Sydney, NSW 2010, Australia.
3266 Merrimon Avenue, Asheville, NC 28801-1218.
Copyright © American Museum of Natural History 2003 ISSN 0003-0082
2 AMERICAN MUSEUM NOVITATES NO. 3407
gap estratigrafico/linaje duende en la historia temprana del grupo Metacryphaeus. También
parte de este grupo, la especie Wolfartaspis liebermani (Formaci6on Icla, Kochis, Depar-
tamento de Cochabamba) antecede a su unico congénere, W. cornutus. Entre los Calmon-
iidae, Granadocephalus hannibali (Formaci6én Icla del Departamento de Cochabamba) es
caracterizada por una combinacio6n de caracteres nueva para la familia. Este género mo-
notipico podria presentar como taxa mas cercanos miembros del grupo Calmonia.
INTRODUCTION which contributes to the taxonomic and
stratigraphic record of Bolivian calmoniids.
Calmoniid trilobites from the Devonian of Morphological terminology follows that used
Bolivia have a long history of study. Since
in the Treatise on Invertebrate Paleontology,
the initial descriptive work by d’Orbigny
Part O (Whittington and Kelly, 1997) as well
(1842), numerous papers have documented a
as the terminology of Eldredge and Branisa
rich diversity in the Lower and Middle De-
(1980). The term Large Eye Index was intro-
vonian (e.g., Kozlowski, 1923; Brani§a, duced by Wolfart (1968), calculated as the
1965; Wolfart, 1968; Eldredge and Ormiston, ratio between the exsagittal length of the eye
1979; Eldredge and Braniga, 1980; Lieber- and the sagittal length of the glabella exclud-
man et al., 1991; Lieberman, 1993). Most ing SO. The chronostratigraphic scheme for
Bolivian calmoniids occur in three forma-
the Devonian of Bolivia is as summarized by
tions localized in distinct geographic areas
Adrain and Edgecombe (1996: fig. 2), after
(fig. 1): the Belén Formation (Belén-La Paz-
Blieck et al. (1996). Specimens studied and
Sicasica region of the West Bolivian Altipla-
figured here are deposited in the collections
no); the Icla Formation (Icla-Padilla region, of American Museum of Natural History
Sierras Subandinas of central Bolivia), and (AMNH), Division of Paleontology (Inver-
the Gamoneda Formation (Tarija region, tebrates), and Museo de Historia Natural de
southern Bolivia). The basal portion of all
Cochabamba (MHNC), Bolivia.
three formations is considered to be time-
equivalent, falling within the “‘Scaphiocoe- SYSTEMATIC PALEONTOLOGY
lia-bearing beds’’ (Isaacson, 1977) recog-
FAMILY CALMONIIDAE DELO, 1935
nized as the Scaphiocoelia Assemblage Zone
GEMELLOIDES, NEW GENUS
by Eldredge and Branisa (1980). Trilobites
occur both within and above this level. The DERIVATION OF NAME: Literally, “‘like Ge-
total stratigraphic range of Calmoniidae in mellus’’, in reference to the name Dalmanites
Bolivia is Late Silurian (Pridoli) (Edgecombe gemellus Clarke, 1890; gemellus (Latin), a
and Fortey, 2000) to Middle Devonian (Giv- twin.
etian). TYPE SPECIES: Gemelloides delasernai, n.
It is now well established that calmoniid gen. and sp.
trilobites are endemic to a Southern-hemi- REFERRED SPECIES: Dalmanites gemellus
sphere biogeographic region that Clarke Clarke, 1890 (= “‘Vogesina’’ gemellus
(1913) first characterized as an ‘‘austral fau- (Clarke) fide Lieberman et al., 1991) is pro-
na’’, which he was able to distinguish from visionally assigned.
a “meridional fauna’’. Richter and Richter DIAGNOsIS: Cephalon twice wider than
(1942) observed the endemic character of long, gently convex (tr. and sag.). All lateral
this fauna and coined the term ‘‘Malvinokaf- glabellar furrows well incised; apodemal part
fric Province’’, which corresponds generally of S1 abruptly shallowing, S1 faintly conflu-
to the Malvinokaffric Realm of Eldredge and ent with axial furrow; S2 effaced abaxially;
Ormiston (1979). S3 steeply inclined exsagittally. Pygidium
Smith and Edgecombe (1996) informally triangular in outline, relatively wide, lacking
reported two new genera and four new spe- marginal spines or lappets; pygidial axis
cies of Calmoniidae from Bolivia, but did not comprises 11 rings (first 5 separated by
name or describe them. In this paper we pre- groovelike impression of distal part of ring
sent a systematic description of this material, furrows, posterior rings progressively weak-
2003 CARVALHO ET AL.: CALMONIID TRILOBITES FROM BOLIVIA 3
Cochabamba
x
V. Granado
Trinidad
* Tarabuco
Padilla
Sania Cruz
Co. Picacho x)
POACCEIAFNI C
ARGENTINA B
Fig. 1. A, map of Bolivia, showing location of inset (map B); B, locations of trilobite collection
sites in this work (indicated by X) relative to major cities and towns.
er); pleural field moderately convex (tr), proximately 16 mm. Axial furrows are very
with at least six ribs. distinct, narrow, weakly divergent, slightly
curved externally at L2. The widest point of
Gemelloides delasernai, new species the glabella (across L3) is approximately 7
Figure 2A, B mm, and its posterior width is 4.9 mm. The
occipital furrow (SO) is deep, moderately
DERIVATION OF NAME: After Salvador de la
wide, curving anteriorly (sag.). Sl is a deep,
Serna, field companion to L. Smith for many
wedge-shaped groove, widest mesially,
years, who helped to collect the material.
sharply narrowing and shallowing distally,
DIAGNOsIs: Lateral glabellar furrows S2
faintly confluent with the axial furrow, pos-
and S3 sharply defined; apodemal part of S1
teromedian part positioned close to SOQ; S2 is
wedge-shaped; sculpture consisting of small,
longer and narrower than S1 (tr.), slightly
strong pits widely distributed on cephalon,
convex forward, with weak posteromedial
thorax, and pygidium, without coarse gran-
orientation, effaced well inward of axial fur-
ules or tubercles.
row; S3 is straight, narrow, widest distally,
TYPES: Holotype: MHNC 8130, external
mold of almost complete specimen (fig. 2A, strongly divergent toward the anterior gla-
B), from the lower part of the Upper Member bellar margin (this margin is not preserved,
of the Belén Formation, layer of Wolfartaspis and it is uncertain whether S3 reaches it); the
cornutus (Wolfart, 1968), late Emsian, Belén strongly divergent arrangement of S3 gives
area, La Paz Department, Bolivia (latex cast rise to a pattern in which the glabellar fur-
AMNH 48073). Paratype: AMNH 48074, in- rows appear to radiate away from the center
ternal mold of part of thorax and external of the glabella. The glabellar furrows do not
mold of frontal glabellar lobe, from type lo- cross the median region of the glabella,
cality. which is not inflated. The glabellar lobes
DESCRIPTION: The cephalon is wider than likewise lack independent inflation; L1 is
long, with length (sag.) of cranidium 7.2 mm narrow mesially, becoming wider near the
and width (tr.) across posterior border ap- axial furrow; L2 is wider than L1 and is trap-
+ AMERICAN MUSEUM NOVITATES NO. 3407
row is straight and moderately wide across
most of its extent, gradually narrowing near
the genal angle. The posterior border is very
narrow adjacent to the axial furrow but is
considerably wider (exsag.) abaxially, with
an evenly convex posterior margin and a
rounded genal angle. The palpebral lobe and
surrounding area of the fixigena are some-
what swollen, sloping down laterally behind
and around the eye. The palpebral lobe is
narrow, bounded by a faint palpebral furrow.
The cephalon (glabella, LO, fixigenal field,
and posterior border) is ornamented with
small, widely distributed pits, but lacks any
granular or tuberculate sculpture.
The thorax comprises 11 segments, all
weakly convex (tr.) with the axial region
somewhat higher than the pleurae. Maximum
axial width is about one- third that of the
thorax. The first four axial rings are faintly
convex forward sagittally; this convexity is
gradually accentuated in more posterior
rings. Axial furrows are shallow and narrow
but well defined. Thoracic pleurae are trans-
verse and horizontal proximally, becoming
weakly flexed posteriorly in the distal por-
tion; this flexure is also more accentuated
posteriorly. Pleural furrows are deep, narrow,
and run straight across the pleurae onto the
articulating facets. The margin of the anterior
pleural band is convex proximally; the pos-
terior band is longer than the anterior (tr.)
and is broader distally (exsag.).
The pygidium is moderately large (9.4 mm
maximum width) and triangular in outline.
The axis is only slightly higher than the pleu-
ral field, defined by shallow, narrow axial
Fig. 2. Gemelloides delasernai, n. gen. and furrows, and includes 11 discernible rings.
sp. Holotype MHNC 8130, Upper Member of Be- The first four rings are gently flexed anteri-
lén Formation, Belén, La Paz Department. A, dor- orly and are separated by broad ring furrows,
sal view of nearly complete specimen, latex cast
which are deepest distally and impressed as
from external mold, scale 2 mm; B, detail of ce-
transverse grooves; the following rings are
phalon, scale 2 mm.
progressively fainter. The axial terminus is
indistinctly defined, but a postaxial field, if
ezoidal, becoming wider laterally; L3 is also present, is short (sag.). The pleural field is
trapezoidal in outline and is larger than L2. gently arched (tr.) and comprises at least six
The posterior median impression is a short ribs. The first three are gently curved poste-
(sag.), elongate pit on the frontal lobe, ante- riorly, but the remaining ribs are more dis-
rior to the tips of S3. The frontal lobe is not tinctly flexed. Pleural furrows are narrow but
inflated or distinguished from the rest of the more distinct than the interpleural furrows,
glabella. LO is moderately arched (tr.), lon- which are only weakly developed. Little of
gest sagittally, distinctly wider than L1, with the pygidial margin is visible, but its exposed
a width of 5.5 mm. The posterior border fur- part (at the ends of the anterior three ribs)
2003 CARVALHO ET AL.: CALMONIID TRILOBITES FROM BOLIVIA m)
lacks marginal spines or lappets. The axial gesina of equivalent size to the holotype of
rings and pleurae of the thorax and pygidium G. delasernai. The glabella is considerably
are ornamented with small pits like those less convex (sag.) in Gemelloides delasernai
covering the cephalon. than in Vogesina and is not significantly el-
DISCUSSION: The close similarity between evated above LO. The pygidium of Gemel-
Gemelloides and Vogesina Wolfart, 1968 in- loides delasernai resembles that of Vogesina
dicates membership in the Malvinella group in lacking marginal lappets, but has a rela-
(sensu Lieberman et al., 1991), and the genus tively broader outline, with the distal part of
possesses more general apomorphies of that the pleurae less steeply turned down than in
group, such as depression of the abaxial part Vogesina. Collectively, these findings sug-
of L1 beneath L2 (character 23 of Lieberman gest that G. delasernai is the sister taxon to
et al, 1991). Vogesina is united with Palpe- Vogesina but can be differentiated as a dis-
brops Lieberman et al., 1991 by a convex tinct taxon on the basis of cephalic as well
(sag.) glabella (Lieberman et al., 1991, node as pygidial characters.
9, character 8), which is shared to a lesser ‘““Vogesina’ gemellus (Clarke), from the
degree by Gemelloides. None of the three Maecuru Formation in the Amazon Basin, is
characters supporting node 10 in their phy- known only from an isolated, poorly pre-
logeny (which pertain to the anterior part of served glabella (Lieberman et al., 1991: fig.
the cephalon and the hypostome) can be de- 8.5, 8.6), and the state of only one of the
termined in our material, but both characters apomorphic characters uniting G. delasernai
supporting their node 11 (Vogesina s.1., char- with V. aspera and V. lacunafera (Lieberman
acters 5, 11) are present (weakly divergent et al., 1991) could be determined. “‘Vogesi-
cephalic axial furrows and steep inclination na” gemellus has a similar glabellar profile
of S3). The latter feature gives rise to a dis- (sag.) and arrangement of lateral glabellar
tinctive radial pattern of glabellar furrows furrows to G. delasernai. We provisionally
which is also weakly evident in Palpebrops, assign it to Gemelloides based on these char-
and may thus represent a synapomorphy of acters, although the generic diagnosis em-
Vogesina, Gemelloides, and perhaps Palpe- phasizes the better known G. delasernai.
brops. Specific distinction between G. gemellus and
Within Vogesina as recognized by Lieber- G. delasernai is made based on the wider
man et al. (1991), V. aspera and V. lacuna- glabellar furrows, more elongated longitudi-
fera are separated from ‘*Vogesina”’ gemellus nal median groove on the glabella, and tu-
(= Gemelloides gemellus here) by 12 char- berculate sculpture of the former species.
acters. Three of these cannot be observed in
the specimens of Gemelloides delasernai, n. Eldredgeia Lieberman, 1993
sp., but this taxon definitely lacks two other
TYPE SPECIES: Metacryphaeus venustus
characters (8, 18; strongly convex glabella;
Wolfart, 1968, from the Sicasica Formation
elongate but nearly effaced S2 and S3) and
(Givetian), La Paz Department, Bolivia. Also
shares seven apomorphies with V. aspera and
known from the Upper Member of the Belén
V. lacunafera (12, 20, 27, 29, 32, 45, 48; S3
Formation, La Paz Department (Lieberman,
straight; absence of coarse spines on lateral
1993).
glabellar lobe L2; LO not elevated above pos-
terior glabellar region; absence of spines on
Eldredgeia eocryphaea, new species
LO; palpebral furrow weak and palpebral rim
low; absence of spines on thoracic axial rings Figure 3A—L
and on pygidial axis). The well-developed DERIVATION OF NAME: “‘Early Cryphaeus’’,
lateral glabellar furrows in Gemelloides de- being geologically an early representative of
lasernai, n. sp. clearly distinguish this form the ““Metacryphaeus group’’.
from all Vogesina spp., which have S2 and DIAGNOsIs: Species of Eldredgeia with the
S3 as shallow to indistinct, typically resem- following unique character combination:
bling thin pencil lines (Wolfart, 1968). This frontal glabellar lobe gently inflated, with
difference between Gemelloides and Voge- rounded profile sloping down to anterior ce-
sina is marked even on external molds of Vo- phalic margin; posterior median impression a
6 AMERICAN MUSEUM NOVITATES NO. 3407
small pit when present. Eyes set above gla- cave forward; S2 is straight, narrower (tr.),
bella; visual surface bearing at least 24 dor- and shallower than both S1 and S3. S1 and
soventral files with maximum of nine lenses S2 are gently directed forward medially,
per file. Genal angle blunt, lacking a spine. whereas S3 is more oblique, diverging an-
Hypostome with pronounced ovoidal macu- terolaterally. SO is weakly curved forward
lae; posterior border only moderately long; medially, of even width (sag., exsag.), with
two pairs of short marginal spines present a U-shaped section and deep apodemal pits
posterolaterally. distally. The lateral glabellar lobes are well
Types: Holotype: MHNC 8129, internal defined and ornamented by coarse granules.
mold of cephalon (fig. 3D—G) with hypo- L1 is narrow (exsag.) in comparison with L2
stome in situ (fig. 3D), from the Lower and L3 and can be traced across the glabella
Member of the Belén Formation, Scaphio- by faint impression of Sl medially. L2 is
coelia Assemblage Zone, Tikani, Estaci6n de more or less rectangular in outline; L3 is
Bombeo, Sicasica, La Paz Department. Para- more wedge-shaped. LO has a uniform width
types: MHNC 12900, pygidium with partial (sag., exsag.) throughout; its posterior mar-
thorax (fig. 3J—L) in same concretion as ho- gin is approximately transverse. In profile,
lotype and probably belonging to same in- LO lies in almost the same plane as the cen-
dividual; AMNH 47147, internal mold of ce- tral part of the glabella. The lateral border
phalon and articulated thorax (fig. 3A—C), furrow is wide but very faint, and it does not
and AMNH 47146, internal mold of pygidi- distinctly separate the lateral border from the
um (fig. 3H, I, both from the Gamoneda genal field. The posterior border furrow is U-
Formation, Cerro Picacho, 17 km S of Taria, shaped in cross-section, deepest near the ax-
Tarija Department. Other trilobites collected ial furrow, and becomes gradually wider be-
from the same stratigraphic interval at Cerro fore curving forward and shallowing distally.
Picacho are Tarijactinoides jarcasensis, Ko- The posterior border is narrower (exsag.)
zlowskiaspis (Romanops) sp., and Gamone- than LO proximally but becomes longer dis-
daspis scutata, all indicative of the Scaphio- tally. Although the genal angles are not well
coelia Assemblage Zone. preserved in either specimen, they are blunt
DESCRIPTION: The cephalon is nearly twice and lack a spine (the cavity behind the ex-
as wide as long and is moderately convex ternal mold of the genal doublure in fig. 3A
(tr.), with a widely pointed and arched out- is not a genal spine). The palpebral lobe is
line. Some details of the anteriormost part of swollen, gently inclined adaxially/posterior-
the cephalon can be observed only in AMNH ly, and is ornamented by granules. The pal-
47147 (fig. 3A—C), as this region is missing pebral furrow is narrow but relatively sharply
in the holotype. The anterior cephalic border impressed along its length. In frontal view
is narrow and extends medially into a short the free cheek is almost vertical and also has
median triangular frontal process. The frontal granular sculpture. The eye projects higher
lobe is subrhomboidal, with a rounded an- than the glabella, with its anterior margin lo-
terior margin and a rounded profile (sag.) cated opposite the anterodistal corner of L3,
with independent convexity from the poste- adjacent to (but still separate from) the axial
rior glabellar region, sloping down to the an- furrow. The posterior margin of the eye is
terior cephalic margin. A pitlike posterior positioned far from the axial furrow, opposite
median impression is present on the frontal the posterolateral corner of L1 (exsag.). The
lobe in the holotype (fig. 3G), well in front visual surface is not well preserved in either
S3, but is indistinct in the paratype (fig. 3A, specimen; the number of dorsoventral files
C). The auxiliary impression system is ob- cannot be determined in the holotype, but
scured by the granulation covering the fron- AMNH 47147 has 24 dorsoventral files on
tal lobe. The axial furrow is slightly diver- the visual surface. In that specimen no more
gent from SO to S1, but becomes more di- than seven lenses are preserved per file, but
vergent from S1 anteriorly. All three pairs of the top of the eye is damaged and the up-
lateral glabellar furrows are well developed permost lenses are missing. In the holotype
and reach the axial furrow on the internal as many as nine lenses are discernible in the
mold. S1 is broad, deep, and distinctly con- longest files, as was probably the case in
2003 CARVALHO ET AL.: CALMONIID TRILOBITES FROM BOLIVIA 7
AMNH 47147. The anterior section of the four-fifths of pygidial width, excluding mar-
facial suture runs parallel to the axial furrow, ginal lappets). The axial furrow is moderate-
and it reaches the anterolateral corner of the ly deep and narrow; the anterior part of the
frontal lobe without cutting across it. axis tapers strongly back as far as the sixth
The hypostome is preserved in situ be- ring, but the remainder is almost parallel-sid-
neath the cephalon of the holotype, but has ed and has a blunt termination that does not
been pushed forward below the doublure and reach the posterior margin of the pygidium.
against the anterior part of the glabella. Thus, The axis is composed of at least eight rings,
the anterior morphology of the hypostome of which the first six are well developed and
(including its anterior margin, border, and the following two are weaker but distinct; a
wing) are hidden from view. The middle ninth ring is faintly defined in the poorly seg-
body is roughly circular and moderately con- mented terminal part of the axis. The first
vex (tr. and sag.). The maculae are very dis- axial ring is markedly arched anteriorly and
tinct, forming a pair of ovoid protuberances somewhat spatulate distally; the second,
positioned abaxially, near to the junction of third, and fourth rings are likewise spatulate
the middle furrow (which is faint) and the distally, but are less arched anteriorly. The
lateral border furrow (which is moderately first five axial rings are separated by broad,
deep); the border furrow maintains about deep ring furrows with apodemes distally;
equal depth posterolaterally and posterome- behind this, ring furrows are shallow and
dially. The lateral border is narrow, slightly transverse. The pleural field has six pairs of
convex, and runs subparallel posteriorly, and ribs defined by wide pleural furrows, sepa-
the posterior border is long (sag.) and slight- rated by narrow and shallow interpleural fur-
ly convex (sag.). The posterior margin is rows; the fourth interpleural furrow is the last
rounded, with at least one pair of small discernible on the internal mold. The ribs
spines posterolaterally and traces of a second gradually increase in obliquity from front to
pair laterally. The posteromedian margin ap- back, and the sixth is strongly oblique and
pears to be gently curved backward, and positioned near to the axis. The anterior five
lacks a median spine. pleurae terminate as spinelike lappets with a
The thorax, in lateral view, is moderately convex anterior margin and faintly concave
convex, with the axis raised above the pleu- posterior margin. The terminal lappet
rae, and is one-third of the thoracic width. (known only from impressions) is wide but
The axial rings are spatulate, shortened (sag.) its shape and length cannot be established
medially, with granular ornament concentrat- from the available material.
ed distally. Apodemal pits are developed in- DISCUSSION: The new species Eldredgeia
ward of the anterolateral edges of the rings. eocryphaea shares numerous detailed simi-
The articulating half ring is located below its larities with EF. venusta, including a narrow
corresponding axial ring. The proximal one- anterior border to the cephalon, with a short
third of the pleural field is more or less hor- median triangular frontal process; the ante-
izontal and the remainder is gently flexed rior part of the frontal lobe is rounded; the
ventrolaterally. Each pleural furrow is deep eye is relatively long (exsag.); the thoracic
and wide, extending straight diagonally and pygidial axial rings have similar shapes;
across the proximal two-thirds of the pleura. the anterior five pygidial pleurae terminate as
The anterior band is narrowest proximally pointed spines; the posterior border of hy-
and longest (exsag.) at the fulcrum; con- postome is relatively long (sag.); and coarse
versely, the posterior band is longest (sag.) granular ornament is widely distributed over
proximally and tapers to the fulcrum. The the cephalon, thorax, and pygidium. These
pleural furrow is effaced distally. The distal features collectively support inclusion of the
extremities of the pleurae are pointed. Gran- new species in the genus Eldredgeia.
ular sculpture is present across most of the Eldredgeia eocryphaea is most readily dis-
width of the pleurae, but is more prominent tinguished from the younger FE. venusta (the
proximal to the fulcrum. type species, also from Bolivia) by its hy-
The pygidium is broadly triangular in out- postome having more pronounced maculae
line, wider than long (length approximately (fig. 3D) and a substantially shorter (sag.)
8 AMERICAN MUSEUM NOVITATES NO. 3407
2003 CARVALHO ET AL.: CALMONIID TRILOBITES FROM BOLIVIA 9
posterior border (see Lieberman et al., 1991: rence of the Metacryphaeus morphotype
figs. 3.6, 3.7 for E. venustus). In addition, the (i.e., the dalmanitiform cephalic morphology
genal angle is blunter (versus more spinelike and five-lappeted pygidial form shared by
in E. venusta) and the visual surface has a Metacryphaeus and allied genera as revised
lower number of dorsoventral files (24 versus by Lieberman, 1993). This morphotype has
26—27 in E. venusta), although the maximum not previously been known from the Sca-
number of lenses per file (nine) is the same Phiocoelia Assemblage Zone. On the basis of
in both species. a late Lochkovian occurrence of Parabou-
Eldredgeia venusta has also been reported leia, a member of the Malvinella subgroup
from the Middle Devonian (Eifelian) of Bra- of the Metacryphaeus group, in Argentina,
zil and South Africa; in South Africa the spe- Edgecombe et al. (1994) inferred that line-
cies is even said to characterize an E. venusta ages of the Metacryphaeus group predated
Zone (Cooper, 1982). Lieberman (1993: 554) their known occurrences in Bolivia. Eldredg-
suggested that the South African and two eia was one of several lineages in the Me-
Brazilian forms probably represent addition- tacryphaeus group that was inferred to have
al, distinct species of Eldredgeia. Eldredgeia an unsampled range extension (or ghost lin-
eocryphaea, n. sp. differs from the South Af- eage) that considerably preceded its first ob-
rican form in having a higher number of dor- served appearance (in late Emsian or Eifelian
soventral files on the visual surface (24 ver- strata in the Upper Member of the Belén For-
sus 18), more lenses per file (nine; the South mation). The discovery of Eldredgeia eocry-
African form has six or seven), the shape of Dhaea in the lower part of the Lower Mem-
the genal angles (blunt rather than pointed), ber of the Belén Formation and equivalent
and glabellar lobes (more inflated in the form Strata in the Gamoneda Formation (both rep-
from South Africa). resenting the Scaphiocoelia Assemblage
The Brazilian form attributed to Eldredg- Zone) closes one of the stratigraphic gaps in
eia from the Amazon Basin (E. paituna the Metacryphaeus group.
(Hartt and Rathbun) from the Ereré Forma-
tion; see Lieberman, 1993: 554) can be dis- Wolfartaspis Cooper, 1982
tinguished from E. eocryphaea, n. sp. in hav-
TYPE SPECIES: Metacryphaeus cornutus
ing a longer (sag.) frontal lobe and S1 with
Wolfart, 1968, from the lower part of the Up-
an accentuated crescent shape. In the other
per Member of the Belén Formation (late
Brazilian form (from the Parnaiba Basin, Pi-
Emsian), La Paz Department, Bolivia.
menteira Formation; see Lieberman et al.,
1991: fig. 2), Sl is more strongly curved
Wolfartaspis liebermani, new species
(adaxially) and LO is longer (sag.). We en-
Figures 4A-F, 5A—F
dorse Lieberman’s (1993) suggestion that the
South African and Brazilian material repre- DERIVATION OF NAME: For Bruce S. Lie-
sents additional species of Eldredgeia, and berman, who has made valuable contribu-
the new form described in the present work tions to systematics and biogeography of cal-
appears to be distinct from all of them. moniid trilobites.
Eldredgeia eocryphaea significantly ex- DIAGNOsIs: Cephalic anterior border weak-
tends the range of Eldredgeia into earlier ly pointed medially; ventral view of cephalon
Stratigraphic intervals than previously triangular in outline. Eyes less than one-third
known. It also represents the earliest occur- glabella length (Large Eye Index 31%); vi-
<
Fig. 3. Eldredgeia eocryphaeus, n. sp. A-C, H, I, Gamoneda Formation, Cerro Picacho, Tarija
Department. All scales 5 mm. A-C, AMNH 47147, dorsal, lateral, and anterodorsal views of cephalon
and articulated thorax, internal mold; H, I, AMNH 47146, dorsal and posterior views of pygidium,
internal mold. D—G, holotype MHNC 8129, internal mold of cephalon, Belén Formation, Tikani, La
Paz Department. All scales 5 mm. D, ventral view of hypostome; E-G, lateral, anterior, and dorsal views
of cephalon; J-—L, MHNC 12900, dorsal, posterior, and lateral views of pygidium. All scales 5 mm.
10 AMERICAN MUSEUM NOVITATES NO. 3407
sual surface with 25—26 dorsoventral files SO) in AMNH 47403 is 23.4 mm, with the
with a maximum of 10 lenses per file. Oc- frontal lobe having marked independent con-
cipital ring strongly arched in cross section, vexity from the posterior glabellar region,
wide medially, with pronounced convex an- which has a flat sagittal profile. The frontal
terior margin and robust median spine taper- glabellar lobe is inflated, about 60% of gla-
ing dorsally. bellar length, and gradually expands anteri-
Types: Holotype: MHNC 8132, external orly and laterally, with its anteromedian mar-
mold of an incomplete cephalon, Icla For- gin rounded. The anterior section of the fa-
mation, equivalent to basal part of Upper cial suture circumscribes but does not tran-
Member at Icla type locality (see Discussion sect the frontal glabellar lobe. The frontal
below), Kochis Hills (approximately 3 km lobe has a well- developed circular to slightly
north of the Rio Grande, on the border be- elongated posterior median impression (PMI)
tween Chuquisaca and Cochabamba Depart- and auxiliary impression system (AIS) of
ments), Bolivia. Paratypes: AMNH 47148, muscle scars. The latter is most clearly pre-
internal mold of thorax and pygidium; served on the left side and the median part
AMNH 47149, internal mold of a cephalon; of AMNH 47403 (fig. 5A) as small rounded
AMNH 47150, external mold of pygidium; pits on the internal mold, forming divergent
AMNH 47151, external mold of an incom- rows. Medially, the AIS does not seem to
plete pygidium; AMNH 47401, hypostome have a defined pattern. The lateral glabellar
in situ beneath cephalon; AMNH 47403, in- furrows are well developed. S3 is wide, deep,
ternal mold of almost complete cephalon; oblique, straight, with its proximal part
MHNC 12749, internal mold of incomplete weakly bent posteromedially, lengthening
pygidium. All type specimens are from the abaxially, and distinctly confluent with the
Icla Formation, Kochis, Cochabamba De- axial furrow. S2 is transverse, narrower and
partment. shallower than S1 and S3; it becomes abrupt-
OTHER MATERIAL: Some additional topo- ly shallow distally and has only faint im-
type specimens collected within the same pression against the axial furrow on the ex-
stratigraphic interval as the types are referred ternal cuticular surface (fig. 4A). S1 is deeper
to Wolfartaspis liebermani, but they are not than S2 and S3; it sharply narrows distally
well preserved. Most are from broken con- but is distinctly confluent with the axial fur-
cretions and include three internal molds and row on the external mold; the posterior mar-
two external molds of pygidia, an internal gin of SI is concave. L3 is wedge-shaped;
mold of four or five thoracic segments, an L2 is approximately trapezoidal; L1 is slight-
external mold of some pleurae, and two in- ly shorter (exsag.) than L2 and L3, with its
ternal molds of cephala. In addition, how- posterior margin markedly convex backward
ever, there is a single, well-preserved, small and then continuing inward, forming a short
pygidium in part and counterpart. This ad- (sag.) transglabellar lobe that is weakly
ditional material is housed in the MHNC col- curved anteriorly; this feature makes the gla-
lection. bella slightly higher at L1 than at L3. SO is
DESCRIPTION: The cranidial length (sag.) is long and relatively shallow (sag.), becoming
about 29.7 mm in AMNH 47403. The ante- shorter and deeper as it approaches the axial
rior cephalic border is narrowest medially, furrow. Where the cephalic posterior furrow
where the upturned doublure nearly contacts meets SO, both have approximately the same
the cranidial margin; the anterior cephalic width; the posterior furrow becomes wider
border projects only slightly in front to the (exsag.) toward the fulcrum, and is then gent-
glabella medially in dorsal view; the anterior ly flexed forward and shallows distally. LO
border gently widens abaxially, but remains is strongly arched in its transverse section,
narrow (exsag.) in dorsal view, and is steep wide medially, with a pronounced convex
along its entire width. The cephalic antero- anterior margin, and bearing a robust median
lateral margin is nearly straight in dorsal spine that tapers dorsally; the median spine
view and is rounded medially. The axial fur- is weakly declined posteriorly. The eye is
row is deep, wide, straight, slightly divergent high, less than one-third glabellar length
forward. Glabellar length (sag., excluding (Large Eye Index 31%). Its anterior edge is