Karlingocelis helfrichi ( Karling, Mack-Fira and Dorjes, 1972 ), 2025

Karlingocelis helfrichi ( Karling, Mack-Fira and Dorjes, 1972) comb. nov.

( Fig. 2 A–H View FIGURE 2 )

Syn. Archimonocelis helfrichi Karling, Mack-Fira and Dorjes, 1972

Diagnosis. Species of Karlingocelis with ovaries about midway between pharynx and brain and around 20 testes in a row in front of the ovaries. Stylet 54–60 µm long, 6–12 µm wide, and with a proximal opening 12–17 µm wide. Two pairs of hooks about 12 µm long. Karyotype: n=5; FN=9.

Occurrence. “Oahu, Kaneohe Bay, Coconut Island, washed out from sand, stones and coral reefs, 16–10 April 1969 ( type locality)” ( Karling et al., 1972).

New material. Hawai’i, O’ahu, Kaneohe Bay, Coconut Island (Lat. 21.434967, Long. –157.787189), 0.2–0.6 m deep at low tide, fine sand; Hawai’i, O’ahu: Sampan Channel, Kanehoe Bay, north side, sandy channel among coral outcrops, coarse sand, at about – 3 m (Lat. 21.461893, Long. –157.782964). Reef 14, Kanehoe Bay, slope of sand bar, coarse sand, – 4.6 m (Lat. 21.459322, Long. –157.801965. Reef 14, Kanehoe Bay, top of sand bar, coarse sand, – 2 m (Lat. 21.463286, Long. –157.809218 ( May 2017).

Hawai’i, Hawai’i Is.: extensive tidal pools near Hilo, sandy patches among coral outcrops, coarse sand at about— 1 m at low tide (Lat. 19.738746, Long. –155.038799) ( June 2017) .

Material studied. The type material, borrowed from the Swedish Museum of Natural History , Stockholm, Sweden, SMNH, and many living specimens and five whole mounts from the newly collected material ( CZM 853–857 ) .

Description. A small and slender species, about 3 mm long, similar in general morphology and topography of internal organs to the previous species. The seminal vesicles are rather large and globular; the prostate vesicle is elongated and upwardly oriented, while the stylet is directed ventrally ( Fig. 2B View FIGURE 2 ). The four short hooks are placed at the very distal end of the slender stylet in some specimens ( Fig. 2 F, G View FIGURE 2 ) or almost half way of the stylet in other individuals (such as in the holotype — Fig. 2 D View FIGURE 2 ) depending on the degree of contraction of the muscular fibres to which they are connected.

Karyotype. With five pairs of evenly-sized chromosomes; four pairs are meta- to submetacentric with low centromeric index, and one pair is formed by heterobrachial chromosomes ( Fig. 2C View FIGURE 2 ).

Remarks. Specimens identified as K. helfrichi comb. nov. have been reported from French Polynesia (Philippe Jouk, pers. comm). Without a direct examination of these specimens, we cannot decide whether this record witness a wide distribution of the species across the Pacific plate, or rather they may point to a further, undescribed species of the genus.