Caulleriella sp.

Blake, James A., 2021, New species and records of Caulleriella (Annelida, Cirratulidae) from shelf and slope depths of the Western North Atlantic Ocean, Zootaxa 4990 (2), pp. 253-279 : 271-272

Caulleriella sp.

Material examined. Massachusetts, Cape Cod Bay, off Manomet Point , approximately 41°55.62′N, 70°32.28′W, among rocks and algal holdfasts, 6–8 m, coll. May 1990, 3 small specimens, one complete (JAB) .

Description. The complete specimen from Manomet Point is a small, mature female, with 30 setigers, 1.9 mm long and 0.25 mm wide across anterior setigers. All segments are short, not beaded, and with widely separated noto- and neuropodia; a ventral groove is present along anterior and middle setigers. In alcohol, the color is opaque white; when stained with Shirlastain A, a prominent internal orange-colored heart body is obvious along the first one-third of the body.

The prostomium is short, tapering to a rounded apex; eyes are absent; nuchal organs were not observed. The peristomium appears to be a single ring, with a distinct dorsal crest. The dorsal tentacles arise from the posterior margin of the peristomium; the first branchiae arise from setiger 1 and continue for about half the length of the body. Notosetae include 2–4 thin capillaries on setigers 1–11, with 1–2 hooks replacing them from setiger 12; neurosetae include capillaries on setigers 1–2, replaced by hooks from setiger 3 with up to 5–6 per fascicle in middle body segments. Hooks bidentate, sigmoid, very small, difficult to study in light microscope possibly ‘alate’ with narrow flange on curved convex side. Pygidium a rounded lobe, with a least one short anal cirrus present. Eggs are present in setigers 12–18, at least two per segment, each large relative to the small size of the worm, ca. 85 µm in diameter.

Remarks. In May 1990, several small specimens of Caulleriella were collected as part of a monitoring program off Manomet Point, a promontory south of Plymouth, Massachusetts, on Cape Cod Bay. The samples were collected by divers who scraped algae and other encrusting materials from the surface of rocks from a depth of about 6– 8 m. At least three different cirratulid polychaetes were identified: Caulleriella sp. , Cirratulus sp. , and Dodecaceria sp. The short description the Caulleriella specimens allows some comparison with Leidy’s (1855) account of C. fragilis from a similar habitat.

History. Caulleriella fragilis was originally described by Leidy (1855) from under intertidal rocks at Point Judith, Rhode Island near the entrance to Narragansett Bay. The species was described as Cirrhatulus [sic] fragilis and was referred to the genus Caulleriella by Chamberlin (1919: 372) in a footnote. The species was also recognized as belonging to the genus Caulleriella by Hartman (1944) as part of her publication of Verrill’s unpublished plates. Hartman (1959) also listed Caulleriella fragilis in her Catalogue. Despite being the oldest named cirratulid from the U.S. Atlantic coast, C. fragilis has rarely been reported and not described since the original report.

Records of Caulleriella fragilis . Leidy (1855: 147) described the species as follows: “ Body cylindrical, narrowed towards the extremities, reddish orange color, posteriorly greenish. Mouth inferior, circular; upper lip conical. Eyes two. Cirri numerous, orange colored; the first pair commencing at the second setigerous segment and the most robust. Setae in two rows, simple, in fasciculi of three to five. Podal hooks in two rows, five to eight in each fasciculus, sigmoid, bifid at the free extremity. Intestine cylindrical, constricted. Ovaries on each side of the intestine, extending four-fifths the length of the body. Worm three lines long, by one-fourth of line broad and composed of forty annulations. Found under stones, on the shores of Point Judith.” Leidy (1855: plate XI, figs. 39–43) illustrates the worm as being long, narrow, and with segments being similar and almost moniliform along the body. The prostomium is large and pear-shaped bearing two large eyespots and followed by a single achaetous segment (peristomium); dorsal tentacles appear to arise on the second setiger, but the points of origin are not indicated. Leidy’s (1855) Fig. 43 shows the pygidium as having two rounded lobes and shows a recurved hook with two apical teeth.

The only subsequent reports of the species are by Verrill (1873) from rocky habitats in Vineyard Sound and Webster (1879) from tidal flats of Great Egg Harbor, New Jersey. Verrill (1873: 397) found the species associated with ascidians on rocky and gravelly bottoms. “ The Cirrinereis fragilis, which is a small and delicate species, furnished with conspicuous eyes, and related to the large Cirratulus , occurs beneath the stones.” Hartman (1944), as part of her unpublished plates by Verrill, assigned Plate 19, fig. 3 to Caulleriella fragilis . This figure illustrates an entire worm in dorsal view and (3a), the same anterior end in ventral view. In this illustration in contrast to that of Leidy, the prostomium is short, conical and bears two small eyespots; this is followed by a peristomium that appears to consist of two rings, the first short and narrow, the second larger which overlaps setiger 1 mid-dorsally. The dorsal tentacles appear to arise from setiger 1 together with the first branchiae. The body segments are short, wider than long. The pygidium consists of a cup-like structure below the anal opening. Setae are not illustrated. This illustration differs from the description and figures of Leidy (1855) in several respects, the most important being differences in the pre-setiger morphology and placement of the dorsal tentacles (setiger 2 in Leidy; setiger 1 in Verrill); as well as different pygidial morphology (two lobes in Leidy and a single cup-like lobe in Verrill).

Webster (1879: 122) identified a specimen as Cirrhinereis fragilis and noted: “ Rare; a single injured specimen was found which probably belongs to this species.” No further information was presented.

As near as can be determined from the literature and personal communications, there have been no other reports of the species from along the U.S. Atlantic coast and no descriptive remarks since the original account 165 years ago by Leidy (1855). There are no existing specimens of C. fragilis from the original collections (M.E. Petersen, in correspondence). The lack of reports of C. fragilis are likely due to their cryptic habitat under rocks and nestled among algae and other encrusting organisms. As a result, the identity and status of C. fragilis based on differences between the original description and illustrations by Leidy (1855) and notes by Verrill (1873) and illustrations by Verrill published by Hartman (1944) represent a modern-day enigma.

Comparison of the Cape Cod Bay specimens with Caulleriella fragilis . The Cape Cod Bay specimens differ from Leidy’s original depiction of C. fragilis in several respects. The new specimens have a relatively short, compact body with short crowded segments; the dorsal tentacles arise from the posterior margin of the peristomium; no eyespots are present; and the pygidium consists of a single lobe with at least one anal cirrus. In contrast, the body of C. fragilis as illustrated by Leidy (1855) is long and narrow with individual segments mostly as wide as long; the dorsal tentacles were said to arise from setiger 2; a pair of eyespots were present; and the pygidium consisted of two rounded lobes lacking anal cirri. The distinctive color pattern reported by Leidy (1855) was apparently from life, precluding any comparison with the new specimens. Both forms are reported as sexually mature females with eggs. Leidy (1855) was explicit in stating that the first and most robust tentacles began on setiger 2. Such a placement of tentacles has not been recorded in other species of Caulleriella . The absence of eyespots in the Cape Cod Bay specimens may be real or possibly due to fading of the pigments after 30 years in alcohol.

Nevertheless, based on experience of dealing with cirratulids for many years, it is my opinion that the Cape Cod Bay specimens represent a different species than C. fragilis as it was originally described and illustrated. The Cape Cod Bay specimens likely represent a species new to science. The placement of the dorsal tentacles, shape of the body, presence or absence of eyespots and pygidial morphology appear to be different between the two forms. The new specimens also differ from Verrill’s illustration of C. fragilis in Hartman (1944). However, the three Cape Cod Bay specimens are fragile and were damaged with each effort to make observations. For this reason, no effort has been made to formally describe them in this paper. It should be possible, however, to collect additional specimens from rocky habitats along the western side of Cape Cod Bay and perhaps elsewhere in New England. The Cape Cod Bay specimens are therefore, being retained for further study with the expectation that additional materials will be obtained. Hopefully, taking a closer look at the smaller invertebrate fauna encrusting or under intertidal rocks will result in additional specimens of the Cape Bay species as well as determine the identity of C. fragilis .