Diplocardia bivesiculata

source: core.ac.uk

A NEW SPECIES OF DIPLOCARDIA FROM FLORIDA

(OLIGOCHAETA; MEGASCOLECIDAE)

W. R. MURCHIE

Department of Zoology, The University of Michigan Flint College, Flint, Michigan

This description is based on 20 clitellate and 6 aclitellate specimens which

I collected in Columbia County, Florida, July 26, 1959. The specific location

was 7 miles southeast of Lake City, along Route 245. All of this work has been

accomplished during the tenure of research grant G-6378, awarded to me by the

National Science Foundation.

Diplocardia bivesiculata n. sp.

Elongate, anterior and posterior ends somewhat swollen. Size, 165-215 by 2.5-3.0 mm.

Somites, 190-241, average 212. Pigment lacking. Clitellum XIII-XVIII dorsally, X I I I -

J^XVII ventrally. Setal formula, aa: ab: be: cd: dd =20: 7: 20: 10: 80. Protomium, epilobic,

one half; margins converging. First dorsal pore in 10/11. Annulations, I-IV simple; V-XII,

bi- or tri-annulate; post-clitellar annulations simple. Anus teminal. Tuberculae pubertates

lacking. Nephropores are in setal line d, at anterior edge of each segment. Genital tumesences

present as distinct papillae in setal line ab of VIII and IX; glandular area is present on ventral

part of XXI or XXI-XXII. Genital setae; setae ab of XVIII and XX very small and con-

fined to body wall. Spermathecal setae; setae ab of VIII and IX about twice the length of

normal setae, distinctly curved, distal one-third strongly sculptured, tip hastate.

Spermathecal pores, two pair, in 7/8 and 8/9, on anterior edges of VIII and IX, in setal

line ab. Spermiducal pores paired, between setal arc and anterior edge of segment in XIX,

on outer edge of seminal gutter. Male field is flat, involves 3-^XVII-XX, between a setal lines.

The seminal gutter is a nearly straight cleft with slightly raised edges, it involves j^XVIII-

HXX. Prostate pores are two pair, equatorial, at ends of seminal gutters. Oviducal pores

paired on oval, fiat field of mid-ventral XIV, located anterior to setal arc about one-half distance

to anterior edge of segment.

Pharynx occupies II, III, IV. Pharyngeal glands compact, confined to II, III, IV. Giz-

zards two, in V and VI. Esophagus includes VII-XIV, ridged internally. Calciferous gland

in XV and XVI; lamellae about 80 in number and free at inner margin. Intestine expands

abruptly in XIX. Typhlosole weakly developed, begins anteriorly in XXIII; posterior ending

variable between LIII-LXXIII. Septa 8/9 and 9/10 much thickened; 7/8, 10/11, and 11/12

thickened; 6/7 and 12/13 slightly thickened. Longitudinal musculature of pinnate type.

Meganephridal; nephridia avesiculate, appearing first in II. Dorsal vessel doubled from XVIII

(XIX, XX?) forward into VII; doubling is intrasegmental only, vessel simplex at penetration

of each septum. Ventral vessel present; subneural vessel absent. Last hearts in XIII.

Testes, two pair, free, branching, in X and XI. Sperm duct without post-septal epididymal

looping; generally free of parietes, ducts of each side joining within the body wall in XIX. Pros-

tate glands two pair, in XVIII and XX. One pair of lobulated seminal vesicles in XII, from

11/12. Single pair of rather flattish ovaries in XIII; ova in multiple string; ovarian funnel

conelike; ovisac absent; oviduct short and direct to body wall of XIV. Seminal receptacles

are two pair, in VIII and IX; ampulla and duct about equal in length; ampulla sub-spherical

and compressed; diverticulum small, deeply incised, located on anterior surface of duct near

the point where the latter enters the body wall. Setal follicles not developed internal to parietes.

Syntypes have been placed in the United States National Museum (U.S.N.M. Cat. No. 30006).

DISCUSSION

No striking variations in the digestive tract were noted among the specimens

examined. The esophageal walls are quite vascular. In segments XV and XVI,

THE OHIO JOURNAL OF SCIENCE 61(3): 175, May, 1961.

176 W. R. MURCHIE Vol. 61

the gut wall does show a characteristic caliciferous gland development (fig. 1-F).

Because the lumen is normally somewhat eccenteric, it is not possible to give the

exact proportion of the gland occupied by the lumen, but at the height of lamellar

development the inside measurements would be 0.067 x 0.40 mm and the respective

outside measurements 0.60 x 0.94 mm. Generally, the lamellae are free at their

inner ends although in a few instances, coalescence does occur forming inter-

lamellar tunnels.

The typhlosole begins quite abruptly in XXIII; the posterior end is indistinct

and can be established anywhere from LIII to LXXIII. The entire typhlosolar

structure does not exceed 0.20 mm in height (fig. 1-E). Its dorsal surface con-

tains a deep groove filled with blood. This groove, or typhlosolar sinus, is con-

FIGURE 1

A. Diagram of ventral aspect of D. bivesiculata.—1. Glandular field of XXI-XXII. 2.

Position of prostatic pore of XX. 3. Spermiducal pore. 4. Seminal gutter. 5. Posi-

tion of prostatic pore of XVIII. 6. Glandular field surrounding oviducal pores. 7.

Glandular area surrounding setae ab. 8. Position of spermathecal pore in 7/8.

B. Distal portion of spermathecal seta IX b.

C. Spermathecal setae IX b.

D. Normal seta X a.

E. Typhlosole of XXX in cross section.—1. Chloragogen cells. 2. Intestinal blood sinus.

3. Typhlosolar epithelium. 4. Typhlosolar blood sinus.

F. Dorsal portion of calciferous gland.—1. Chloragogen cells. 2. Muscle layer. 3.

Lamella of gland. 4. Intra-lamellar sinus.

G. Spermatheca of segment IX.—1. Ampulla. 2. Diverticulum.

H. Prostate of segment XVIII.—1. Glandular portion. 2. Ectal portion of duct.
No. 3 NEW DIPLOCARDIAN OLIGOCHAETE 177
tinuous with the general blood sinus of the intestine, the Darmblutsinus of Hertling
(1923).
Intra-segmental doubling of the dorsal vessel is easily determined from XVIII
forward into VII. Behind XVIII, removal of the chloragogue layer reveals the
vessel to be apparently doubled in XIX. In XX, the vessel is flattened and in
this area it may be perforate medially. The simplex condition obtains at each
point where the vessel penetrates a septum.
Sculpture of the spermathecal setae (setae ab of VIII and IX) is strong (fig.
1-B and C); the tip is hastate but subject to fracture so that this characteric must
be used diagnostically with some care. Setae ab of XVIII and XX are exceed-
ingly small. Their dimensions, based upon saggital sections, are estimated to be:
0.005 x 0.034 mm in width and length respectively. These setae, in each segment
bearing them, are nearly contiguous and close to the prostatic pore. I could not
find them in gross dissection.
The two pairs of spermathecae, in VIII and IX, are equal in size. The ampulla
is ovoid, compressed, and contains some sperm. Similarly, the deeply incised
diverticulum contains sperm and is located on the anterior side of the duct near
its penetration of the body wall (fig. 1-H). Externally the spermathecal pore is
obscure but an elliptical glandular spot surrounds the opening in 7/8 and 8/9
(fig. 1-A). This glandular area is actually confined to the anterior edge of VIII
and IX but presses into the intersegmental furrow.
The prostates are similar in size and general form. The duct of each is
thickened, coiled, and about twice the length of the glandular portion (fig. 1-H).
The anterior pair of prostates occupy segment XVIII with the glandular part
normally confined to this segment and with its long axis extending in a transverse
plane. Anteriorly, the duct may extend a loop into XVII, but in no example
studied did the duct penetrate XIX. The posterior postates, of XX, lie with
their long axes in the antero-posterior plane; the glandular portion penetrates
XXI and the duct may extend into XIX and XXI.
Although Diplocardia bivesiculata has but a single pair of small seminal vesicles
in XII, segments X and XI are filled with sperm and it is probable that the cavi-
ties of these segments function as seminal vesicles.
Inasmuch as we do not know how much significance to attach to the various
features presently employed in the diagnosis of diplocardians, intrageneric affinities
are quite uncertain. Of the described species, bivesiculata would appear to stand
close to Diplocardia eiseni (Michaelsen, 1894) in possessing: (1) a doubled dorsal
blood vessel anterior to XX; (2) reduction in the setae of prostatic segments; (3)
quadrithecate condition; and (4) the presence of a pair of hearts in XIII. The
major differences between bivesiculata and eiseni would be: (1) reduction in
number of seminal vesicles in bivesiculata; (2) position of spermathecal pores;
and (3) the position of the calciferous gland.
Diplocardia bivesiculata was collected from the compacted soil of a vehicular
trail through a slash pine forest. Worms were common along the trail and at its
edges, but I could not find them in the forest floor proper. The understory of
the forest was palmetto, oak saplings, shrubs, and dense grass cover.
Many of the soil castings were fresh and certainly had been produced within
a few hours at most from the time of collection (3:00 PM). The digestive tract
of all specimens examined was filled with sand from the upper soil layers and
contained little organic material. In terms of habitat occupancy, bivesiculata is
to be considered an upland soil species, in contrast to species preferring leaf litter,
logs, or emergent shore lines.
LITERATURE CITED
Hertling, H. 1923. Untersuchungen tiber dei Typhlosolis und ihre Vascularisierung bei terri-
collen Olteochaeten. Zeit. wiss. Zool. 120: 147-250.
Michaelsen, W. 1894. Die Regenwurm Fauna von Florida und Georgia. Zool. Jahrb. Abt.
f. syst. Okol. u. Geogr. d. Tiere 8: 177-194.