Jasmineira regularis form 1 Hartman, 1978  

Jasmineira Langerhans, 1880

Jasmineira cf. regularis Hartman, 1978 (form 1)

Voucher specimens. Sea Lion: station 79MFB.

Diagnosis. Small sized species; voucher complete (including branchial crown), 6mm long plus 3mm for crown and 0.4mm wide; 8 thoracic and 24 abdominal chaetigers; chaetigers never bead-like, always longer than wide, crowded posteriorly; colour in alcohol pale yellow.

Branchial crown with 5 pairs of radioles; with 2 pairs of non-vascularised ventral radiolar appendages, about half the length of radioles; where missing, branchial crown with a typical Jasmineira-abscission zone.

Collar is well-developed, higher ventrally than dorsally, with smooth anterior margin, and ventrally with an obvious mid-ventral notch less than half the length of collar; dorsally forming two pockets separated by a median gap.

Narrow glandular ridge around chaetiger 2.

Collar chaetae narrowly-hooded arranged in oblique rows. Following thoracic chaetigers with narrowly-hooded superior chaetae, about 3 per fascicle and paleate inferior chaetae with long mucron, about 5 per fascicle. Thoracic neuropodial uncini acicular, with several rows of minute, similar-sized teeth covering half the length of main fang; reducing in number from chaetiger 2 with 8 uncini in a row to 4 in chaetiger 8 (the last thoracic chaetiger). Companion chaetae absent. Abdominal chaetigers with few elongate, narrowly-limbate (hooded) chaetae. Abdominal uncini avicular (S-shaped), elongated, about 7 arranged in a single row in chaetigers 9 (first abdominal chaetiger), diminishing number posteriorly to 2 in the last abdominal chaetiger; with five rows of similar-sized teeth, occupying half the length of main fang; reduced breast and medium-length handle.

Posteriomost chaetigers gradually narrowing into blunt triangular pygidial lobe; pygidial eyespots not observed. Tube not observed.

Remarks. Several species in genus Jasmineira were collected from Falkland Islands in this study and these are summarised in table below as well as comparative image of staining patterns. These cannot be unambiguously assigned to the species previously reported from the area, mostly due to limitations of existing descriptions and the fact that branchial crowns are often missing. Specimens with 24-28 abdominal chaetigers and 5 pairs of radioles (and as additionally observed 2 pairs of nonvascularised ventral radiolar appendages) when branchial crown attached, or 7 scars observed on abscission zone where branchial crown missing, were intially assigned to Jasmineira regularis as these correspond well with the original description Hartman (1978). However, eventually two forms emerged among these specimens with different shape of posterior end and some differences in staining patterns (see comparative table and comparative images).

Further, Jasmineira sp. 2, Jasmineira sp. 3 and J. cf. regularis (itself having 2 forms) are very similar to each other, mostly differing in number of radiolar pairs (where possible to establish or at least estimate from abscission zone), number of abdominal segments and body shape of posterior end and pygidium as well as methyl green patterns. Additionally two more Jasmineira species with number of abdominal segments greater than 30 were distinguished Jasmineira sp. 1 with lateral as well as ventral incisions on collar and Jasmineira sp. 4, which differs in its body shape, with segments having shallow, but distinct constrictions giving them somewhat bead-like appearance. Of the species known from the area (see table below) only Jasmineira crumenifera Hartmann-Schröder, 1986 has over 30 abdominal segments, however it is unclear which (if any) of the specimens encountered here belong to this species and examination of the holotype is required.

Comparison of characters of Jasmineira species known from the area as reported in literature and Jasmineira species collected from Falkland Islands in this study.