Perinereis larentukana

Perinereis larentukana (Grube, 1881) Fig. 8 E – G Nereis larentukana Grube, 1881: 110–111. Neanthes larentukana. – Hartman 1959: 250. Wiktor 1980: 273. Nereis larentukana. – Hartwich 1993: 111. Perinereis larentukana comb. nov. by Villalobos-Guerrero 2019: 483 –488, figs 1 G – I, 8 A – L, 9 A – F. Type locality. East Nusa Tenggara, Indonesia. Material examined. MZB.Pol.00246 (9 specimens), collected by Joko Pamungkas on 23 March 2015 from Saparua Island: Saparua Village, Saparua District, Central Maluku Regency, Maluku Province (3°34'24.9"S, 128°39'26.7"E); SMF 33469 (2 specimens), collection details as in MZB.Pol.00246. MZB.Pol.00249 (13 specimens), collected by Joko Pamungkas on 5 October 2009 from Nusalaut Island: Akoon Village, Nusalaut District, Central Maluku Regency, Maluku Province (3°40'16.3"S, 128°48'35.1"E); MZB.Pol.00303 (55 specimens), collected by Geterudis Kerans on 20 April 2024 from Pero Batang Village, Kodi District, Southwest Sumba Regency, East Nusa Tenggara Province (9°36'26.8"S, 118°59'07.1"E); MZB.Pol.00307 (6 males) and MZB.Pol.00308 (1 female), collected as heteronereids locally known as nyale by Dewi C. Murniati on 8 March 2018 from Lombok Island: Seger Beach, Kuta Village, Pujut District, Central Lombok Regency, West Nusa Tenggara Province (8°54'25.9"S, 116°17'49.3"E). Comparative material. Perinereis nuntia. ZMH - ANN-P 18075 (2 specimens). Diagnosis. Prostomium with antennae joined medially and nuchal organs three times longer than posterior eyes. Postero-dorsal tentacular cirri reaching chaetigers 2–3. Pharynx with conical paragnaths on both rings, smooth bars present on Areas VI, arranged as follows. Area I = 2–3; Area II = 7–9; Area III = 9–17, 1 lateral cone; Area IV = 20–28, merged paragnaths absent; Area V = 3–4, paragnaths behind Area VI; Area VI = 4–8, arc short, regular, bars short, even, except inner one slightly longer; Areas VI – V – VI pattern, υ-shaped (ridges of VI sub-medially markedly separated, parallel furrows); Areas VII – VIII = 26–34 in two transverse rows, proximal with large cones. Gap between Area VI and Areas VII – VIII broad. Dorsal cirri short, one-half length of dorsal ligule, posteriorly, inserted at two-thirds of dorsal ligule. Dorsal ligule even throughout body, subequal to median ligule; distal lobe bluntly conical posteriorly. Ventral cirri short and digitiform. Homogomph spinigers with finely serrated blades, evenly spaced, absent in subacicular neurochaetae. Heterogomph spinigers as notopodial; absent in a few anterior chaetigers. Heterogomph falcigers with short and medium blades (modified after Villalobos-Guerrero 2019). Distribution and habitat. The species was found in East Nusa Tenggara and Maluku Provinces, Indonesia, inhabiting intertidal sandy shores. Remarks. The specimens in the present study agree well with previous descriptions. The body color of P. larentukana from Saparua Island tends to be light maroon, whereas the species from Nusalaut Island tends to be whitish. As the species has not been reported elsewhere, P. larentukana appears to be endemic to Indonesia. Perinereis larentukana is considered a member of Perinereis nuntia species complex, mainly by having conical paragnaths on both pharyngeal rings, an arc of several shield-shaped paragnaths arranged in a row on Area VI, notochaetae with only homogomph spinigers, and slightly uneven dorsal and median ligules throughout the body (Wilson and Glasby 1993; Glasby and Hsieh 2006; Villalobos-Guerrero 2019). This study is the first report of P. larentukana occurring among reproductive nyale (the species is one of the biggest nyale worms). The reproductive-stage specimens obtained in the present work, swarming as nyale worms, complement the collection of this species at MZB. Perinereis larentukana appears to be one of the most common Indonesian species inhabiting sandy beaches in the eastern and western (Pari Island, off Jakarta, pers. obs. CJG) parts of the country. Because of its relatively large body size, P. larentukana is often utilized by the locals as fishing bait.