Indopacifica selirongensis Ermilov & Marshall, 2026, sp. nov.
Year: 2026
Type: article
Abstract: Indopacifica selirongensis sp. nov. (Figs 6A–C; 7A–K; 8A–D; 9A–D; 10A, B) Type material. Holotype (male) and four paratypes (three males and one female): Brunei, inner Brunei Bay, Pulau Selirong, 4°53 ’ N, 115°6 ’ E, estuarine environment, benthic substratum with mangrove Rhizophora roots, June 2025 (collected by Lee Huan Chiao). The holotype is deposited in the Senckenberg Museum of Natural History, Görlitz, Germany. Three paratypes are deposited in the University of Tyumen, Tyumen, Russia. One paratype is in the personal collection of the first author. All specimens are preserved in 70% ethanol with a drop of glycerol. Additional material. Four adults (collected from the type locality) were used for SEM. Diagnosis (adult). Body length 300–345. Body cerotegument homogeneous, represented by dense, small tubercles. Lamellar seta longer than rostral and interlamellar setae. Bothridial seta clavate/fusiform, barbed. Anterior margin of notogaster indistinct medially. One pair of slightly oblique ridges developed lateral to lenticulus. Fourteen pairs (c 3 absent) of notogastral setae short, setiform, smooth. Adoral seta or 1 slightly phylliform, with acicular apex, while or 2 shorter, slightly phylliform. Three pairs of adanal setae present. Adanal lyrifissure slightly oblique, located anterolateral to anal aperture. Leg trochanters III and IV anterodorsally with triangular process. Description of adult. Measurements. Body length 345 (male holotype), 300–330 (male paratypes), 330 (female paratype). Body width 195 (male holotype), 173–210 (male paratypes), 195 (female paratype). Integument (Figs 7A–D, H; 8A–D; 9A–D; 10A, B). Body color brown. Surface microporose and partially microsculptured with simple and oblong microtubercles (visible under high magnification in dissected specimens and via SEM; Fig. 9C). It covered with distinct layer of cerotegument, represented by dense, small, homogeneous tubercles, and partially obscured by dirt. Prodorsum (Figs 6A, C; 7A, C, D, H; 8A, C, D; 9A, B). Rostrum rounded, with narrow depression behind rostral margin (Figs 7H; 9A). Transverse furrow (often appearing as ridge in dorsal view) between rostral and lamellar setae present (Figs 7A; 8A, C). Lamella completely reduced in dorsal view (Figs 7A; 8A), but its outline discernible in lateral view (Figs 7C; 8C). Centrodorsal region with indistinct longitudinal elevations and depressions (Figs 7A; 8A, C). Rostral (11–13), lamellar (15–17), and interlamellar (11–13) setae setiform, thin, smooth. Bothridial seta (45–52) clavate/fusiform, with densely barbed head. Bothridium with lateral incision and triangular tubercle filling space of this incision (as in S. bruneiensis sp. nov. and T. bandarensis sp. nov.; Figs 17C; 25B). Exobothridial seta (4) acicular. Notogaster (Figs 6A, C; 7A, C, D; 8A, C, D; 9B). Anterior margin of notogaster indistinct medially (Fig. 7A). Lenticulus diffuse (Fig. 7A). One pair of slightly oblique ridges developed lateral to lenticulus (Figs 7A; 8A). Region between anterior margin of notogaster and setae of c -series with indistinct depressions (Figs 8A, C; 9B). Fourteen pairs (c 3 absent) of notogastral setae (19–22) setiform, smooth. Opisthonotal gland opening and all lyrifissures slightly visible. Gnathosoma (Figs 7I–K; 8B, D; 9C). Generally, similar to S. bruneiensis sp. nov. Subcapitulum size 86–90 × 60–64. Anterolateral part of rutellum quadrangular (visible under high magnification in dissected specimens, whereas in intact specimens it may illusory appear triangular). Subcapitular seta m (26) setiform, roughened, setae a (19) and h (26) setiform, smooth. Adoral seta or 1 (15) slightly phylliform, with acicular apex (Fig. 7I), seta or 2 (7) slightly phylliform. Palp length 64–67, setal formula 0-2-1-3-9(+1ω). Postpalpal seta (2) spiniform. Chelicera length 75–82, setae (cha 22; chb 15) setiform, barbed. Epimeral and lateral podosomal regions (Figs 6B, C; 7B–D; 8B–D). Medial region of epimere I slightly depressed. Epimeral setal formula 2(1)-0-1-1, seta 1c represented by alveolus, sometimes completely reduced, seta 1b (41–45) setiform, smooth, setae 3b and 4a (both 7) acicular. Pedotectum I represented by small lamina. Discidium large, triangular. One pair of lateral podosomal tubercles simple. Anogenital region (Figs 6B, C; 7B–D, F; 8B, D; 9D; 10A). Anogenital setal formula 3-0-2-3. Genital (7–9), anal (5), and adanal (5) setae acicular. Adanal seta ad 1 located lateral or posterolateral, ad 2 and ad 3 located lateral to anal aperture, sometimes asymmetrically. Adanal lyrifissure slightly oblique, located anterolateral to anal aperture. Legs (Figs 7E, G; 8A–D; 10B). Generally, similar to S. bruneiensis sp. nov. Claw of all tarsi strong, sparsely barbed on dorsal side and with one tooth mediobasally (Fig. 10B). Porose area on segments not visible. Trochanters III and IV anterodorsally with triangular process (Fig. 7G). Formulas of leg setation and solenidia: I (0-3-2-3-18) [1-2-2], II (0-3-2-3-15) [1-1-1], III (1-2-1-2-13) [1-1-0], IV (1-2-1-3-12) [0-1-0]. Homology of setae and solenidia indicated in Table 1. Notes: Tr, Fe, Ge, Ti, Ta = trochanter, femur, genu, tibia, and tarsus, respectively. Prime (ʹ) and double-prime (ʺ) indicate anterior and posterior setae of a pseudosymmetrical pair. Parentheses refer to both members of the pair collectively. Remarks. In having three pairs of adanal setae, the adult of I. selirongensis sp. nov. is similar to that of I. pantai Pfingstl, Shimano & Lienhard, 2018 from the Oriental region. However, the new species can be distinguished from the latter by the morphology of the body cerotegument (homogeneous, with small tubercles vs. heterogeneous, with large and small tubercles) and the presence of one pair of slightly oblique ridges in the anterior part of the notogaster. Etymology. The specific epithet selirongensis refers to the place of origin, Pulau Selirong.
Authors: Ermilov, Sergey G., Marshall, David J.
Institutions: University of Tyumen, Universiti Brunei Darussalam
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225617458
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