Cryptonome americana ( Hartman, 1951 ), 2024

Cryptonome americana ( Hartman, 1951) View in CoL new combination

Figs 6 View FIGURE 6 and 7 View FIGURE 7

Pareurythoe americana Hartman, 1951: 25-28 View in CoL , Pls 6, 7.

Diagnosis. Cryptonome with median antenna longer than laterals; parapodial cirri smooth; branchiae short, not covering dorsum, first one with about 20 filaments; harpoon-notochaetae with one series of denticles.

Type material. Texas, U.S.A. Paratype ( LACM 102 About LACM ), epitoke, Padre Island , 6 Jul. 1933 (another label indicates March 1942), C.T. Reed, coll. Paratype ( LACM 103 About LACM ), Port Aransas , 15 Dec. 1947, J.W. Hedgpeth, coll. (both with labels, written on 18 Mar. 2016, J.D. Kudenov indicated they do not belong in Pareurythoe . He was correct) .

Description. Paratype (LACM 103) complete, twisted, colorless; 72 mm long, 3 mm wide, 98 chaetigers; six parapodia previously removed from chaetigers 9 (right), 22 (right), 30 (right), 36 (left), 45 (left), 77 (left), not in container; right parapodium of chaetiger 40 removed for observation (kept in container).

Body tapered posteriorly, anterior and posterior regions depressed; anterior end contracted; integument with longitudinal furrows ( Fig. 6A View FIGURE 6 ).

Prostomium with a shallow anterior indentation, about twice longer than wide ( Fig. 6B View FIGURE 6 ); anterior prostomial lobe with medially swollen lateral antennae, directed dorsally, as long as palps; palps directed ventrally, lateral antennae and palps smooth, non-articulated. Posterior prostomial lobe with median antenna as wide as laterals, about twice longer than them. Caruncle small, cushion-shaped, not visible dorsally. Peristomium reduced to two fusiform, longitudinal medially separated cushions; mouth between chaetigers 2–3.

Parapodia all biramous, larger anteriorly, progressively smaller posteriorly. Notopodia and neuropodia conical, notopodia larger than neuropodia. Dorsal and ventral cirri smooth, dorsal cirri tapered, 4-5 times longer than ventral fusiform cirri ( Fig. 6C View FIGURE 6 ).

Branchiae from chaetiger 3, continued along body, missing in last 2-3 chaetigers. Branchial filaments larger, more abundant along chaetigers 5–30, with 6–7 basal stems, with about 20 filaments in chaetiger 3, and about 40 filaments in chaetiger 40. Posterior chaetigers with less filaments (five filaments close to last branchiferous segments). Branchial filaments digitate throughout body.

Chaetae variably damaged after formaline preservation. Notochaetae of two different sizes, longer ones smooth capillaries, shorter ones harpoon-chaetae with a few lateral denticles (difficult to observe). Neurochaetae in median chaetigers only furcates, with a very small, short tine (spurred) ( Fig. 6D View FIGURE 6 ). No other chaetae observed.

Posterior end tapered ( Fig. 6E View FIGURE 6 ); pygidium with anus terminal, lacking anal cirri.

Epitoke. Paratype ( LACM 102 About LACM ), female, colorless, anterior end previously cut off (kept in container); right chaetiger 20 removed for observation. Anterior region removed after an oblique transverse cut, with five parapodia on the left, and six on the right side, 2.5 mm long, 3.6 mm wide (excluding chaetae), 9 mm wide (including chaetae); rest of body 155 mm long, 10 mm wide (without chaetae), 108 chaetigers.

Anterior end already dissected for observing caruncle ( Fig. 7A View FIGURE 7 ). Median antenna tapered; caruncle low, short, sinuous fleshy lobe, about as long as median antenna, obliterated by contracted portions of adjacent parapodial surfaces. Lateral antennae without ceratostyles. Branchiae start in chaetiger 3 ( Fig. 7B View FIGURE 7 ), continue almost to the last chaetiger.

Parapodia variably damaged. Anterior region with collapsed parapodia, most with ventral cirri contracted ( Fig. 7C View FIGURE 7 ), with abundant oocytes. Dorsal cirri irregularly contracted ( Fig. 7D View FIGURE 7 ). Oocytes with well-defined nucleus and nucleole, each about 100 µm in diameter ( Fig. 7E View FIGURE 7 ).

Median and posterior parapodia better preserved. Chaetae markedly longer than parapodial lobes. Chaetae include only smooth capillaries (probably after being in formaline for a long time).

Posterior region tapered; pygidium with anus terminal; anal cirri not seen.

Remarks. Pareurythoe americana Hartman, 1951 is newly combined into Cryptonome by having a barely developed caruncle, as long as or shorter than median antenna. As indicated in the key above, C. americana ( Hartman, 1951) n. comb. separates from other species having straight caruncle such as C. elongata ( Treadwell, 1931) n. comb. from the Caribbean Sea, by having about 20 branchial filaments in the first branchiae, whereas the others have about 10 filaments.

On the other hand, Hartman (1951: 28) noted that the epitoke, being collected in 1933, had some pigmentation remaining when she studied it. For example, she indicated eyes were large, and that chaetae were fine, notochaetae transparent (white), and neurochaetae pale yellow and thicker. No pigmentation remains now in the specimen.

Distribution. The species was described with specimens from Florida and Texas, U.S.A. However, no depth or other ecological data were given. Rioja (1958: 224) recorded it, with hesitation, from Veracruz, México. He indicated the caruncle could reach chaetiger 2.