Chicoreus ( Triplex ) phyrtos, Houart & Russini & Fassio & Oliverio, 2025

Houart, Roland, Russini, Valeria, Fassio, Giulia & Oliverio, Marco, 2025, Developmental types and a new cryptic species of Chicoreus (Gastropoda: Muricidae) from Papua New Guinea, Zootaxa 5723 (2), pp. 245-267 : 261-263

Chicoreus ( Triplex) phyrtos sp. nov.

Fig. 6A–P urn:lsid:zoobank.org:act:

Etymology. FROm The ancIenT GReek φυρτός, LaTInIZed phyrtos , meaning mixed. This name is used here because illustrations of Chicoreus microphyllus in previous publications are probably a mixture of two species.

Type material.

Holotype. PAPUA NEW GUINEA • 1 lv, ad; Kranket Island , PAPUA NIUGINI stn PR90; 05°12' S, 145° 49' E; 55.4 mm; MNHN-IM-2013-14939 .

Paratypes. PAPUA NEW GUINEA • 1 lv, juv; E Tab Island , PAPUA NIUGINI stn PR4; 05°10' S, 145°51' E; 30 m; outer slope; 32.5 mm; MNHN-IM-2013-10234 • 1 lv, juv; Padoz Reef , PAPUA NIUGINI stn PR12; 05°9' S, 145°48' E; 2–30 m; 31.2 mm; MNHN-IM2013-15254 • 1 lv, ad; Kranket Island , Cape Jantzen, PAPUA NIUGINI stn PR16; 05°12' S, 145°49' E; 13 m; 58.2 mm; MNHN-IM-2000-40288 • 1 lv, 1 ad; East Wonad Island , PAPUA NIUGINI stn PR53; 05°8' S, 145°49' E; 20 m; 72.3 mm; MNHN-IM-2013-13871 • 1 lv, ad; Kranket Island , Cape Jantzen, PAPUA NIUGINI stn PR97; 05°12' S, 145°49' E; 58.6 mm; MNHN-IM-2000-40289 • 1 lv, juv; Kranket Island , Cape Jantzen, PAPUA NIUGINI stn PR97; 05°12' S, 145°49' E; 19.9 mm; MNHN-IM-2013-15318 .

Type locality. Papua New Guinea, Kranket Island , 05°12' S, 145° 49' E .

Distribution. Specimens of Chicoreus phyrtos sp. nov. with intact protoconch or having been subjected to a molecular analysis were only collected in Papua New Guinea, living at 2–30 m depth.

Description. Shell up to 72.3 mm in length at maturity. Length/width ratio 2.06–2.12. Slender, lanceolate, narrowly ovate, heavy, weakly spinose and nodose. Subsutural ramp narrow, weakly sloping, weakly concave; broader and more strongly sloping in early whorls.

Shell dark brown or blackish brown, lighter coloured in interspaces of primary spiral cords and between primary and secondary cords. Occasionally with lighter coloured spiral cords, forming broad, cream to light brown spiral bands; lighter coloured 6 or 7 first teleoconch whorls. Ventral part of siphonal canal whitish on left side. Subsutural uniformly dark brown. Aperture bluish-white within, columellar lip and outer lip light orange for a short distance within.

Spire high, acute, with 2.50–2.75 protoconch whorls and teleoconch up to 10 moderately broad, convex, elongate, weakly shouldered, spinose and nodose whorls. Suture of whorls impressed. Protoconch small, conical, acute, with a strong, narrow, single keel abapically, otherwise smooth; whorls convex, glossy; maximum width and height 1000 µm; terminal lip delicate, raised, curved, of sinusigera type.

Axial sculpture of teleoconch whorls consisting of axial ribs on first whorl and low strong narrow, nodose varices and axial ribs from second to last whorl. First whorl with 10 or 11 ribs, second to last whorl with 3 narrow, rounded, moderately high varices and 2 or 3 intervarical, nodose ribs from second to antepenultimate whorl. Last whorl with 3 or 4 intervarical ribs. Spiral sculpture of low, rounded, narrow, squamous and nodose primary, secondary and tertiary cords, and additional numerous threads. Subsutural ramp with adis, IP and additional threads, followed by P1, s1, P2, s2, P3, s3, P4, s4, P5, s5, t, on convex part of whorl and ADP, ads, MP, ms, ABP, abs on siphonal canal. Additional several strongly nodose, narrow threads between primary and secondary cords and on top of primary cords P1–P6 and ADP, MP, MP which extend as short, broad, frondose spines on varices. P1 spine short, P2 spine shorter, then spines increasing in length abapically, P6 cord with longest spine. Secondary cords ending as short, ventrally bent, open spinelets between primary spines.

Aperture moderately large, ovate. Columellar lip narrow with weak, low, or moderately high knobs on entire length of outer edge and high, narrow parietal tooth at adapical extremity. Anal notch deep, narrow. Outer lip strongly crenulated with short lirae within, extending as strong crenulations at lip. Siphonal canal short, 26–29% of total shell length, moderately narrow, straight, strongly dorsally recurved at tip, narrowly open ventrally, bearing 3 frondose, short spines extending from spiral cords. ADP and MP spines weakly adapically recurved at tip, ABP spine shortest, abapically bent, occasionally with an additional abs.

Operculum dark brown, ovate, with apical nucleus.

Remarks. Chicoreus phyrtos sp. nov. is morphologically indistinguishable from C. microphyllus ( Fig. 5A, F–R ) except in having a 2.50–2.75 whorls conical protoconch with a sinusigeral notch, indicating a planktotrophic larval phase vs C. microphyllus with 1.75–2.5 rounded protoconch whorls indicating a lecithotrophic larval development.

A shell with broken or strongly eroded protoconch cannot be correctly identified using any other morphological character of the shell.

The protoconch of Chicoreus phyrtos sp. nov. is similar to that of C. torrefactus (G.B. Sowerby II, 1841) ( Fig. 5C ) once considered a synonym of C. microphyllus (e.g. Radwin & D'Attilio 1976: 39). However, C. torrefactus is clearly different molecularly, and differs morphologically from both C. phyrtos sp. nov. and C. microphyllus in having a broader last teleoconch whorl, a columellar lip with a usually smooth or smoother outer edge and a characteristic notch at abapical extremity of that lip ( Fig. 5B ), a feature already noted by Houart (1984: 57, text fig. 4) to separate C. torrefactus from C. dovi Houart, 1984 . Both C. phyrtos and C. microphyllus lack this distinctive notch ( Fig. 5A ).

Chicoreus akritos Radwin & D'Attilio, 1976 also differs in the protoconch morphology, having 2–3 rounded whorls, but also usually differs in having a more variable shell morphology with broader or/and longer varical spines and a comparatively broader last teleoconch whorl relative to the width of the previous whorls.

Figures

FIGURE 5 A–B. Detail of the columellar lip. A. Chicoreus microphyllus (Lamarck, 1822), Papua New Guinea, Hansa Bay (Madang Province), Laing Island, RH; B. Chicoreus torrefactus (G.B. Sowerby II, 1841), PAPUA NIUGINI, stn PR111, Papua New Guinea, 05°08' S, 145°49' E, 10-37 m, MNHN, 45.7 mm. C–E. Chicoreus torrefactus (G.B. Sowerby II, 1841), PAPUA NIUGINI, stn PR111, 05°08' S, 145°49' E, 10-37 m, MNHN, 45.7 mm. F–R. Chicoreus microphyllus (Lamarck, 1822). F–G. Locality unknown, lectotype MHNG 1099/22, 61.2 mm (reproduced from a slide by J. Dajoz); H–J. MONTROUZIER stn 1240, New Caledonia Sector of Touho, between Touho Bay and Atit Island, 24°47' S, 165°14–15' E, 0–2 m, MNHN-IM-2018-1789; K–L. SANTO 2006, E Aoré Island, Mambeto Point, 15° 34' S, 167°13' E, 12 m, MNHN-IM-2009-4998, 50.0 mm; M–N. Papua New Guinea, Hansa Bay (Madang Province), Laing Island, RH, 61.4 mm; O. Philippine Islands, Balabac Island, 10–30 m, RH, 57.6 mm; P–R. Belep Islands, North New Caledonia, RH, 16.9 mm. Red dot: specimen with protoconch examined. Scale bars: 2 cm (A, B), 0.5 mm (C, J, R).

FIGURE 6 Chicoreus (Triplex) phyrtos sp. nov. A–C. PAPUA NIUGINI stn PR90, Papua New Guinea, Kranket Island, 05°12' S, 145° 49' E, holotype MNHN-IM-2013-14939, 55.4 mm; D–E. PAPUA NIUGINI stn PR97, Papua New Guinea, Kranket Island, Cape Jantzen, 05°12' S, 145°49' E, paratype MNHN-IM-2000-40289, 58.6 mm. H–I. PAPUA NIUGINI stn PR53, Papua New Guinea, East Wonad Island, 05°8' S, 145°49' E, 20 m, MNHN-IM-2013-13871, 72.3 mm. J–L. PAPUA NIUGINI stn PR12, Papua New Guinea, Padoz Reef, 05°9' S, 145°48' E, 2–30 m, MNHN-IM2013-15254, 31.2 mm. M–P. PAPUA NIUGINI stn PR97, Papua New Guinea, Kranket Island, Cape Jantzen, 05°12' S, 145°49' E, MNHN-IM-2013-15318, 19.9 mm. Red dot: specimen with protoconch examined. Scale bars: 0.5 mm.