Caulleriella filiformia, Blake, 2021

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 : 256-259

Caulleriella filiformia new species

Figures 1–2

urn:lsid:zoobank.org:act:263E4535-116F-490F-8ABC-0726725F0F29

Caulleriella sp. B : Maciolek et al. 1987a: D-2 (in part); 1987b: D-2 (in part); Hilbig 1994: 940 (in part)

Caulleriella sp. 3 : Blake et al. 1987: C-2 (in part); Hilbig 1994: 940 (in part).

Material examined. (48 specimens) Southeastern USA, off Charleston , South Carolina, U.S. South ACSAR Program, coll. J.A. Blake, Chief Scientist. Sta. 15: Cruise SA-5, Rep. 2, 18 Sep 1985, 32°11.99ʹN, 76°42.23ʹW, 1991 m, holotype ( USNM 1642576 ) ; Rep. 1, 18 Sep 1985, 32°12.00ʹN, 76°42.23ʹW, 1988 m, 2 paratypes ( USNM 1642575 ) ; Rep. 3, 18 Sep 1985, 32°11.97ʹN, 76°42.24ʹW, 1991 m, 1 paratype ( USNM 1642577 ) ; Cruise SA-4, Rep. 1, 16 May 1985, 32°12.02ʹN, 76°42.18ʹW, 1993 m, 1 paratype ( USNM 1642572 ) ; Rep. 2, 16 May 1985, 32°12.05ʹN, 76°42.18ʹW, 1991 m, 4 paratypes ( USNM 1642573 ) ; Rep. 3, 16 May, 1985, 32°10.74ʹN, 76°42.93ʹW, 2003 m, 2 paratypes ( USNM 1642574 ) .— Off New England, U.S. North Atlantic ACSAR Program, coll. G.W. Hampson, Chief Scientist. Sta. 5: Cruise NA 3, Rep. 1, 04 Jul 1985, 40°05.11ʹN, 67°29.84ʹW, 2058 m, (3, USNM 1642578 ) ; Cruise NA 4, Rep 2, 25 Nov 1986, 40°05.09ʹN, 67°29.84ʹW, 2071 m (2, USNM 1642579 ) ; Rep. 3, 25 Nov 1985, 40°05.07ʹN, 67°29.81ʹW, 2071 m (1, USNM 1642580 ) ; Cruise NA 5, Rep. 1, 29 Apr 1986, 40°05.06ʹN, 67°29.94ʹW, 2052 m (2, USNM 1642581 ) ; Rep. 3, 29 Apr 1986, 40°05ʹ.01ʹN, 67°29.90ʹW, 2085 m (2, USNM 1642582 ) ; Cruise NA 6, Rep. 1, 26 Jul 1986, 40°05.07ʹN, 67°29.08ʹW, 2063 m (1, USNM 1642583 ) ; Rep. 3, 26 Jul 1986, 40°05.09ʹN, 67°29.67ʹW, 2055 m (1, USNM 1642584 ) . Sta. 6: Cruise NA 2, Rep. 1, 29 Apr 1985, 40°05.04ʹN, 67°29.99ʹN, 2108 m (1, USNM 1642585 ) ; Rep. 2, 29 Apr 1985, 40°05.03ʹN, 67°29.13ʹN, 2108 m (1, USNM 1642586 ) ; Rep. 3, 29 Apr 1985, 40°05.06ʹN, 67°29.13ʹN, 2107 m (1, USNM 1642587 ) ; Cruise NA 5, Rep. 2, 30 Apr 1986, 40°05.11ʹN, 67°29.21ʹN, 2110 m (2, USNM 1642588 ) ; Rep. 3, 01 May 1986, 40°05.10ʹN, 67°29.13ʹW, 2109 m (1, USNM 1642589 ) . Sta. 8: Cruise NA 2, Rep. 1, 28 Apr 1985, 40°10.24ʹN, 67°37.16ʹW, 2185 m (1, USNM 1642590 ) ; Cruise NA 4, Rep. 3, 25 Nov 1985, 40°10.25ʹN, 67°37.41ʹN, 2182 m (4, USNM 1642591 ) ; Cruise NA 6, Rep. 2, 27 Jul 1986, 40°10.23ʹN, 67°37.25ʹN, 2193 m (2, USNM 1642592 ) ; Rep. 3, 27 Jul 1986, 40°10.21ʹN, 67°37.28ʹN, 2188 (3, USNM 1642593 ) . Sta. 14: Cruise NA 2, Rep. 1, 05 May 1985, 39°40.91ʹN, 70°54.17ʹW, 2095 m (4, USNM 1642594 ) ; Rep. 2, 5 May 1985, 39°40.93ʹN, 70°54.21ʹW, 2092 m (1, USNM 1642595 ) . Sta. 15: Cruise NA 2, Sta. 15, Rep. 2, 5 May 1985, 39°40.07ʹN, 70°54.27ʹW, 2145 m (1, USNM 1642596 ) ; Rep. 3, 6 May 1985, 39°40.10ʹN, 70°54.31ʹW, 2140 m. (1, USNM 1642597 ) .— Off New Jersey and Delaware, U.S. Mid- Atlantic ACSAR, Program, coll. R. Petrecca, Chief Scientist. Mid-6, Sta. 2: Rep. 3, 13 Nov 1985, 38°35ʹ.83ʹN, 72°53.91ʹW, 1994 (3, USNM 1642598 ) .— Off New Jersey, U.S. EPA DWD-106 Site Survey, R. Petrecca, Chief Scientist: Sta. G, Rep. 3, 18 Nov 1985, 38°55.60ʹN, 72°02.62ʹW, 2509 m (1, MCZ 161720 ) .

Description. A long, thin, threadlike species ( Figs. 1A–C , 2A, C–E ); holotype complete, 9.1 mm long, 0.16 mm across anterior segments and 0.12 mm across far posterior segments, for 58 setigers; one complete paratype (USNM 1642576), 8 mm long for 60 setigers. Body generally cylindrical throughout, with no evidence of dorsal or ventral grooves.All segments moniliform to some extent ( Fig. 2A, C–F ); 5–8 anteriormost setigers relatively short, constituting thoracic region ( Figs. 1A–B , 2A–B ), about 1.5–2.0 times as wide as long, then segments becoming longer, about 1.5 times as long as wide ( Fig. 1A , 2A, C–E ); posterior segments becoming shorter, rounded, about as long as wide, weakly moniliform ( Figs. 1C , 2F ), continuing to pygidium bearing two narrow anal cirri ( Figs. 1A , 2F–G ). Individual segments along most of body transparent, with intestinal track and coelom clearly apparent ( Fig. 2A–F ); heart body evident in anteriormost segments of some specimens; epidermis of anterior and middle body segments lumpy, but not producing transverse annulations. Color in alcohol opaque white, with no pigment apparent on body.

Pre-setiger region narrow, about 2.3 times as long as wide, about as long as first four setigers ( Figs. 1A–B , 2A–B ). Prostomium triangular, tapering to narrow rounded apex ( Fig. 1A–B ); eyespots absent; nuchal organs not observed. Peristomium elongate, narrow, with weak lateral grooves in anterior one-third, not producing annular rings ( Figs. 1A , 2A ); holotype with grooves producing lateral pockets ( Fig. 1B ). Dorsal tentacles widely spaced, arising from near posterior border of peristomium ( Fig. 1A–B ); first pair of branchiae arising immediately posterior to dorsal tentacles on peristomium; second pair of branchiae arising on posterior border of setiger 1, dorsal to notosetae ( Fig. 1A–B ). Subsequent segments with branchiae in similar position; branchiae long, thin, present along most of body to near posterior end.

Parapodia reduced; anterior segments with weakly developed podial lobes from which setae arise. Noto- and neuropodial setal fascicles distinctly separated from one another anteriorly, becoming widely separated from one another in middle and posterior setigers. Noto- and neurosetae of anteriormost setigers with 5–8 long capillaries per fascicle; notoacicular bidentate hooks first present from setigers 7–10 (setiger 8 in holotype); neuroacicular hooks similar in distribution (beginning setiger 7 in holotype). Hooks mostly replacing capillaries, 1–3 per fascicle at first, increasing to 4–5 in middle and posterior segments, reduced to 1–3 in far posterior segments. Hooks with a thick, slightly curved shaft tapering to thick main fang surmounted by a thin apical tooth as an extension of an ‘alate’ flange on convex side of shaft ( Figs. 1D–E , 2H–I ); neuropodial hooks shorter and thicker ( Fig. 1D ) than notopodial hooks ( Fig. 1E ). Hooks of far posterior segments becoming longer, less curved, prominently visible on segments anterior to pygidium.

Pygidium with two short anal cirri ( Figs. 1C , 2F–G ); one or both sometimes missing, but scars or stubs usually present.

Variability. The most obvious variability among the material is with the beaded or moniliform segments. In some specimens all segments are at least weakly moniliform with anterior segments short and rounded, middle segments elongated and posterior segments again short and rounded. In other specimens the anterior most segments while distinctly separated from one another are weakly crowded, but transition to moniliform segments along most of the body. In other specimens the middle body segments and some posterior segments appear to be stretched or pulled out, thus obscuring the moniliform shape. Finally, the middle segments of other specimens have an intestinal fold that when filled with particles, elevates the dorsum of individual segments thus exaggerating the moniliform appearance.

Methyl Green staining. No pattern.

Remarks. Caulleriella filiformia n. sp. is distinctive among species of Caulleriella in having a long, thin threadlike body with most specimens having moniliform or bead-like segments along nearly the entire length; segments are short and beadlike in anterior and posterior segments, longer in middle segments and stretched, but still weakly moniliform in shape.

Caulleriella filiformia n. sp. is closely related to C. rodmani n. sp. (see below) with which it may occur. In C. filiformia n. sp. the first pair of branchiae arise lateral to the dorsal tentacles on the posterior margin of the peristomium; the second pair and subsequent branchiae occur on setiger 1 dorsal to the notosetae. In contrast, the first pair of branchiae of C. rodmani n. sp. arise dorsal to the notosetae on setiger 1. Rounded or moniliform segments typically occur along the entire of body of C. filiformia n. sp., while only the first 3–5 thoracic segments of C. rodmani n. sp. are rounded. Two short anal cirri occur on the pygidial segment of C. filiformia n. sp., whereas the pygidium of C. rodmani n. sp. is rounded and lacks anal cirri. One or two of the anal cirri may be damaged or broken, but scars or stubs are usually apparent when stained with Shirlastain A. The bidentate hooks of C. filiformia n. sp. have an ‘alate’ flange on the convex side that forms the apical tooth, whereas in C. rodmani n. sp., there is no flange and the apical tooth emerges directly from the shaft.

Biology and Habitat. One paratype (USNM 1642573) has a few large eggs in posterior parapodia that measure up to 350 µm in the longest dimension; the large size suggesting direct development. Sediments associated with Sta. 15, the type locality off Charleston, SC, were sampled on only two surveys ( Blake et al. 1987). Samples were collected in water depths of 1944–2003 m: SA-4 (May 1985) and SA-5 (Sep 1985). The sediments consisted of 64.1% sand and 35.9% silt + clay on SA-4 and 62.3% sand and 37.7 % silt + clay on SA-5 ( Blake et al. 1987). Thus, the sediments were about 2/3 sand and 1/3 silt + clay. The fauna was dominated by Microrbinia linea Hartman, 1965 a common threadlike orbiniid polychaete that was often the most abundant invertebrate in benthic samples in 2000–3000 m depths throughout U.S. South Atlantic study area ( Blake et al. 1987; Blake 2021). Caulleriella filiformia n. sp. ranked sixth out of the 20 most abundant taxa, but comprised only 2.8 % of the total fauna ( Blake & Grassle 1994). Sites off New England where C. filiformia n. sp. was collected were in depths of 2055–2193 m.

Etymology. The epithet filiformia is an adjective derived from the Latin, filum, a thread, in reference to the thin, threadlike body of this species.

Distribution. U.S. Atlantic continental slope, off New England to the Carolinas, 1944–2185 m.

Figures

FIGURE 1. Caulleriella filiformia n. sp. Paratype (USNM 1642572); A, anterior end, dorsal view: Holotype (USNM 1642576): B, anterior end, dorsal view; C, posterior end, dorsal view; D, neuropodial hook; E, notopodial hook.

FIGURE 2. Caulleriella filiformia n. sp. A, Anterior end, left lateral view; B, Anterior end, dorsal view; C, mid-body setigers, dorsal view; D, transition from mid-body to posterior setigers, dorsal view; E, posterior setigers, dorsal view; F, far posterior setigers with pygidium; G, pygidium dorsal, view; H, notopodial hook; I, neuropodial hook. A, G, I (Sta. 15, SA-4, Rep 2, USNM 1642573); B–E, H (USNM 1642577); F, holotype (USNM 1642576). Stained with Shirlastain A.