Kritzlerius anomalus, Londoño-Mesa, 2009

Londoño-Mesa, Mario H., 2009, Terebellidae (Polychaeta: Terebellida) from the Grand Caribbean region 2320, Zootaxa 2320 (1), pp. 1-93 : 72-74

Kritzlerius anomalus sp. nov.

Figures 21 A-H

Genus A, Kritzler, 1984:52–62, 63; Figs 52–59, 60A-G.

Type material: Holotype USNM 90513 Texas, Off Port Isabel (20°10'N 96°24'W), STOCS Sta. IV-3, XI.1977; 91m. Paratypes: USNM 90514 (1) Off Florida, Gulf of Mexico (24°47'07"N 83°13'05"W), SOFLA Sta. 58, XI.1980; 58m. USNM 90515 (1) Texas, Off Port Isabel (20°10'N 90°31'W), STOCS Sta. IV-6, Autum.1977; 65m. USNM 56040 (1) Gulf of Mexico (29°43'29.3"N 87°54'30.3"W), R/V "Columbus Iselin" Sta. 2640, XI.1977; 35m.

Etymology: The name “ anomalus ” belongs to the adjective that means diverging from the usual, and refers to the abnormal or atypical condition in which the two kinds of tentacles are presented in two separated groups on the tentacular membrane.

Description: Holotype incomplete, 19 segments, 8.5mm long, 1mm wide. Thorax dorsally smooth ( Fig. 21A ). Upper lip well developed, long, projecting forwards. Lower lip reduced as an anterior ventral edge ( Figs 21B,C ). Distal half of long tentacular membrane with two transverse lobes projected laterally on dorsal surface; lobes carrying short thin tentacles ( Fig. 21D ); then, long and thick tentacles in two lateral groups at base of tentacular membrane. Eyespots amber, arranged in two lateral groups irregularly distributed. Ventral shields flat, not clearly differentiated or separated. Ventral groove absent. Branchiae with filaments emerging radially; first pair with 15 and 10 filaments, second pair with 9 and 12 filaments, on left and right side of body, respectively; second pair of branchiae placed anteriorly and separated from notopodia. Nephridial papillae and notopodial glandular tissue not seen. Seventeen pairs of notopodia; notochaetae of two types ( Fig. 21E ), long, straight, unilimbate ( Fig. 21F ); and short smooth, unilimbate, curved distally ( Fig. 21G ). Neuropodia with uncini avicular ( Fig. 21H ) with dental formula MF:5–6:4–6; PP and PF absent; Oc slightly convex; Cp with two series of accessory teeth over the MF, first row with 5–6 teeth as long as one third the MF, second row with 4–6 teeth as long as one half those on first row; Sr narrow; SrP and SrA absent; LSr flat without any square button; AP rounded; AF absent; Bs curved only in middle region. Pygidium not present.

Staining pattern: Posterior dorsal margin of tentacular membrane, base of branchiae and dorsum on segments 3–5 stain slightly ( Fig. 21A ); ventral shields on segments 1–12 stain deeply, with those in segment 12 small and separated ( Fig. 21B ). Other structures not stained.

Variations: All paratypes are incomplete. Larger paratype (USNM 90514) has 22 segments, 20 chaetigers, 23.5mm long, 1.6mm wide. Medium sized paratype (USNM 56040) with 19 segments, 17 chaetigers, 15mm long, 1.5mm wide. First 6 segments are long, and because the first notopodia is separated from the branchiae, it is not easy to identify if it belongs to segment 3 (last segment with branchiae) or segment 4. The use of methyl green indicates that the first pair of notopodia arise from the same segment as last pair of branchiae (segment 3). Smaller paratype (USNM 90515) has 12 segments, 7mm long, 1.6mm wide.

Discussion: Kritzlerius anomalus sp. nov., is the only species described in this new genus. The species seems to have more that 20 thoracic segments with notopodia as the longest specimens found, although incomplete, have 22 segments, and of these 20 have notopodia. This new species is easily recognized by the special morphology of the tentacular membrane in having two separated groups of tentacles on the dorsum; and chaetae unilimbate subdistally curved and distally pointed. No other genera and species in the subfamily Thelepodinae exhibit this characters.

Type locality: Off Port Isabel , Texas, USA .

Distribution: Upper Gulf of Mexico. From 35 to 91m.

Figures

FIGURE 21. Kritzlerius anomalus gen. nov., sp. nov., (Holotype USNM 90513): A. Anterior thoracic region in dorsal view. B. Anterior thoracic region in ventral view. C. Anterior end in ventral view. D. Anterior and in dorsal view. E. Fascicle of notochaetae from chaetiger 1. F. Long notochaetae from chaetiger 1. G. Short notochaetae from chaetiger 1. H. Uncini from chaetiger 13. Scale bars: A: 2.1mm;B: 1.9mm; C,D: 0.4mm; E: 0.9mm; F,G: 0.08mm; H: 0.04mm.