Thelepus tenuis ( Verrill, 1900 ) Londoño-Mesa, 2009

Londoño-Mesa, Mario H., 2009, Terebellidae (Polychaeta: Terebellida) from the Grand Caribbean region 2320, Zootaxa 2320 (1), pp. 1-93 : 85

publication ID

https://doi.org/ 10.11646/zootaxa.2320.1.1

DOI

https://doi.org/10.5281/zenodo.5324870

persistent identifier

https://treatment.plazi.org/id/03F75303-AE0A-FFEA-FF7E-FEC33DCF82EB

treatment provided by

Felipe

scientific name

Thelepus tenuis ( Verrill, 1900 )
status

comb. nov.

Thelepus tenuis ( Verrill, 1900) View in CoL comb. nov.

Figures 26 View FIGURE 26 A-G

Protothelepus tenuis, Verrill, 1900:662 View in CoL .

Euthelepus tenuis, Caullery, 1915:46–47 View in CoL .— Hartman, 1959:505.— Holthe, 1986b:156.

Thelepus tenuis, Hutchings & Glasby, 1986:114 View in CoL .

Type material: Holotype slide YPM 2864 About YPM Bermuda, no more data.

Additional material: YPM 97587 (1) Hungry Bay , Bermuda, 15.VIII.1975; in sand .

Description: Holotype incomplete, on slide, poor condition; 19 segments, 6mm long, 1.1mm wide ( Figs 26A,B View FIGURE 26 ). Upper lip short, rounded. Lower lip slightly swollen. Tentacular membrane short, not clearly visible. Eyespots absent. Some tentacles present, short. Ventral shields, branchiae and nephridial papillae unrecognizable ( Figs 26C,D View FIGURE 26 ). Sixteen pairs of notopodia; notochaetae lanceolate, in two intercalated lengths ( Fig. 26E View FIGURE 26 ). Thoracic uncini ( Figs 26F,G View FIGURE 26 ) with dental formula MF:2:1–3; PP and PF absent; Oc slightly convex; Cp with two lines of teeth, the first line with two teeth, larger than those on second row, and as long as one half of MF; Sr narrow; SrP transformed in long rectangular button without visible SrA, place near a rounded AP; AF absent; Bs curved anteriorly and somewhat flat near the PP. Pygidium missing.

Staining pattern: This pattern was identified in the additional material. Only dorsal tissue, and ventral shields from the first 5 segments stain deeply ( Figs 26B,D View FIGURE 26 ). Other structures not stained.

Variations: Only one additional specimen was collected and identified by Dr. M.L. Jones. This small specimen is complete, but divided in two pieces. It has 78 segments, 11.5mm long, thorax 4.2mm long, 0.4mm wide, 22 pairs of notopodia. Eyespots absent. Two pairs of incomplete branchiae, first pair missing the right branchia, second pair missing the left one; branchial filaments from segment 2 at least as long as 12 thoracic segments; filaments from segment 3 as long as four thoracic segments. Thirteen ventral poorly defined shields from segment 2, first shield the widest, then decreasing in width. Abdominal uncini with dental formula MF:2:5. Pygidium smooth, last 7–8 segments thinner than the previous abdominal segments. Segments 2–4 stain deeply dorsally as well as the first 3 ventral shields; the rest of structures not stained.

Discussion: This species was described by Verrill (1900) as the type species of a new genus Protothelepus Verrill, 1900 , allied to Euthelepus , and distinguished mainly because of the presence of a single pair of long branchial filaments arising, doubtfully, from segment 3 (first segment with notochaetae). Later, Caullery (1915) considered the genus to be possibly invalid because, as it has happened in Eugrymaea Verrill, 1900 , the number of [segments with] branchiae was not important for establishing terebellid genera. Thus, he considered Protothelepus a junior synonym of Euthelepus . Nevertheless, Euthelepus has lateral lappets on segments 2–3 or sometimes 2–4. Therefore, since Verrill did not mention lateral lappets, Hutchings and Glasby (1986) questionably referred this species to Thelepus . I agree considering this generic placement after a thorough revision and comparison of type and non-type specimens. They have the same type of chaetae and uncini with the same dental formula. Besides, after staining, it is confirmed that the specimen from Bermuda has two pairs of branchiae, as stated by Hutchings and Glasby (1986). Eyespots are absent in both species, although the original description stated its presence.

This species is similar to Thelepus crassibranchiatus in having two pairs of single branchial filaments on segments 2–3; nevertheless, T. tenuis has chaetae lanceolate and uncini MF:2:1–5, with long square button on the Sr. Thelepus crassibranchiatus has chaetae paleate and uncini MF:2, with a small square button on the Sr.

Type locality: Bermuda .

Distribution: Only known from Bermuda.

YPM

Peabody Museum of Natural History

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Terebellida

Family

Terebellidae

Genus

Thelepus

Loc

Thelepus tenuis ( Verrill, 1900 )

Londoño-Mesa, Mario H. 2009
2009
Loc

Thelepus tenuis, Hutchings & Glasby, 1986:114

Hutchings, P. A. & Glasby, C. J. 1986: 114
1986
Loc

Euthelepus tenuis

Holthe, T. 1986: 156
Hartman, O. 1959: 505
Caullery, M. 1915: 47
1915
Loc

Protothelepus tenuis

Verrill, A. E. 1900: 662
1900
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