Inella ” longissima ( Dall, 1881 )

Fernandes, Maurício Romulo, 2024, The deep-sea species of Triphoridae (Gastropoda, Triphoroidea) from Guadeloupe, sampled by the Karubenthos 2 expedition, European Journal of Taxonomy 972, pp. 1-52 : 6-12

“ Inella ” longissima ( Dall, 1881)

Figs 2–5

Triforis (Ino) longissimus Dall, 1881: 80 .

Triforis (Inella) longissima – Dall 1889a: 246, pl. 20 fig. 10; 1889b: 138, pl. 20 fig. 10.

Triphora longissima – Abbott 1974: 112, fig. 1138 (a reproduction of Dall’s illustration).

Inella longissima – Garcia & Lee 2002: 11. — Rolán & Fernández-Garcés 2008: 100, figs 10, 36d (the latter is a reproduction of Dall’s illustration). — Rosenberg et al. 2009: 645. — Lamy & Pointier 2018: 286, pl. 91 fig. 8a–b.

“ Inella ” longissima – Fernandes & Pimenta 2019a: fig. 3j.

non Inella triserialis Dall, 1881 – Lamy & Pointier 2018: 286, pl. 91 fig. 9.

Type material

Lectotype CUBA • sh; off Havana; 23°09′00″ N, 82°21′30″ W; depth 320 m; Blake 1877–1878 Exped.; MCZ 7381 .

Material examined

GUADELOUPE (Karubenthos 2 expedition) • 2 sh, worn; stn DW4508; MNHN • 16 sh and 1 spec. stored dry; stn DW4549; MNHN • 2 sh; stn DW4550; MNHN • 5 sh; stn DW4554; MNHN • 9 sh and 1 spec. stored in ethanol; stn DW4555; MNHN-IM-2019-20012 (for the live specimen) • 1 sh; stn DW4556; MNHN • 2 sh; stn DW4572; MNHN • 3 sh; stn DW4577; MNHN • 1 sh; stn DW4589; MNHN • 5 sh; stn DW4592; MNHN • 18 sh and 2 spec. stored dry; stn DW4613; MNHN • 1 sh and 1 spec. stored dry; stn DW4615; MNHN • 5 sh; stn DW4634; MNHN • 1 sh; stn DW4637; MNHN • 8 sh; stn DW4646; MNHN .

Emended description

Shell sinistral, conical-fusiform, up to 20.1 mm long (adult shells reach at least 8.7 mm in length), 2.8 mm wide, length/width ratio 5.5–7.1, apical angle of early whorls 13–15°. Protoconch paucispiral, 2.5–3.0 whorls, 0.55–0.64 mm long, 0.42–0.62 mm wide; first whorl smooth, slightly to considerably inflated, sometimes with same width as subsequent whorls; subsequent whorls with two main spiral cords (situated at 35–44% and 65–70% of last whorl height), the abapical one slightly to considerably more prominent, in addition to a narrow subsutural cord; transition to teleoconch gradual, nearly indistinct. Teleoconch with up to 30 whorls; two spiral cords (adapical and abapical) in beginning of teleoconch, continuous with those of protoconch; median spiral cord emerges narrowly between fourth and eighth whorls, bordering close to adapical cord and slowly developing, reaching nearly same size as abapical cord (adapical one more prominent) only in body whorl of large shells; suture shallow, with a small sutural cord; 19–21 opisthocline axial ribs on 12 th teleoconch whorl; medium-sized, rounded to slightly elliptical nodules; nearly smooth subperipheral cord, with one or two smooth, very thin basal cords right below subperipheral cord; a weak supranumerical cord may form between median and abapical spiral cords; rounded to slightly elliptical aperture, 0.88–1.24 mm long, 0.67–1.09 mm wide, length/width ratio 1.1–1.5; anterior canal can be moderately long, partially to almost closed, 0.38–0.97 mm long, 0.30–0.43 mm wide, length/width ratio 1.0–2.1; posterior canal as a deep sinus and almost detached from aperture, or as a rounded orifice, completely detached from aperture. White shell.

Large eyes. Operculum thin, semi-transparent, nearly rounded to elliptical, multispiral, nucleus subcentral, dislocated 19% from center toward margin.Jaw with scales varying in shape, but mostly rectangular (12.5–14.4 mm long, 3.5–4.0 mm wide, ratio length/width 3.3–3.8), rectangular-bilobed (11.4–16.5 mm long, 4.4–6.1 mm wide, ratio length/width 2.1–3.7) or composed of irregular, large polygons (up to 18.1 mm long), sometimes square. Radula 12-1-1-1-12, with little differentiation in teeth morphology; central tooth comb-like, with five elongated cusps, central and marginal cusps slightly shorter and thinner than cusps 2 and 4; lateral teeth comb-like, with five elongated cusps, marginal cusps slightly shorter, marginal and central cusps slightly thinner than cusps 2 and 4; M1–M11 with four elongated cusps, gradual narrowing of teeth from M1 to M11, as well as shortening of cusps 1 (especially) and 4, which are ~74% of length of cusps 2 and 3 in M1, instead of ~42% (cusp 1) or ~64% (cusp 4) of length of cusps 2 and 3 in M11; M12 reduced, with three cusps (after complete reduction of former cusp 1 in other marginal teeth), central one more elongated than lateral cusps; central tooth up to 4.0 µm wide, lateral teeth up to 4.3 µm wide, M1 up to 3.5 µm wide, M12 up to 1.3 µm wide.

Remarks

“ Inella ” longissima was previously recorded from Guadeloupe (between 200 and 500 m) by Lamy & Pointier (2018). In addition, they applied the name Inella triserialis ( Dall, 1881) to a very similar morph from Martinique. The few apparent differences between these two morphs are the smaller shell length (10 mm in the figured shell of the morph named as I. triserialis vs 20.7 mm in the figured shell of “ I.” longissima ) and the earlier development of the median spiral cord in the supposed I. triserialis . Adult shells from Karubenthos 2 also show a broad range in length (8.7–20.1 mm), which results in large differences with respect to where the median spiral cord of the teleoconch emerges (between the fourth and eight whorls, respectively in small and large shells). However, there is little variation in the dimensions and number of protoconch whorls (2.5–3.0), the more or less inflated first protoconch whorl and certain teleoconch features (e.g., the number of axial ribs). I cannot split the current identification of “ I.” longissima from Guadeloupe in more than one species, and I regard I. triserialis from Martinique ( Lamy & Pointier 2018) as conspecific.

The protoconch of “ I.” longissima from Guadeloupe matches that of a juvenile from the Florida Keys, USA ( Rolán & Fernández-Garcés 2008: fig. 10f), which was up to now the only image of a protoconch of this species. The only inconsistency between the shells from Florida, Bahamas and Cuba described by Rolán & Fernández-Garcés (2008) and those from Guadeloupe ( Lamy & Pointier 2018; this study) is related to which spiral cord is slightly more prominent on the teleoconch: in the first study it is the abapical one, whereas in Guadeloupe it is the adapical one. The shell with unspecified locality shown by Rolán & Fernández-Garcés (2008: fig. 10b, g) is certainly from another species if compared to shells from Guadeloupe, with the adapical cord even weaker than the median cord in later whorls. The welldeveloped, almost closed posterior canal of “ I.” longissima is illustrated in shells from Guadeloupe ( Fig. 4J ; Lamy & Pointier 2018: fig. 8b) and in the lectotype ( Dall 1889a, 1889b).

Dall (1889b) put the northern limit of “ I.” longissima at Cape Hatteras, North Carolina ( USA), and the southern limit in Cuba (but the species is also present in the Florida Keys and in the ‘West Indies’, a term which comprises Cuba). The record from Cape Hatteras, reproduced by Abbott (1974) and Rosenberg et al. (2009), seems to be a mistake, because Dall (1889b) did not list the species for the so-called ‘districts’ in the respective columns, from New Jersey to Biscayne Bay (Florida). This species seems to be mostly from the Caribbean deep sea, apparently extending northwards to Louisiana, USA ( Garcia & Lee 2002, 2020; although not illustrated). The records from Brazil provided by Rios (1985, 1994, 2009) are erroneous ( Fernandes & Pimenta 2019a).

There are errors in the literature in relation to the bathymetric range of “ I.” longissima . Rolán & Fernández-Garcés (2008) cited 175 m as the depth for the lectotype (repeated by Bakker & Albano 2022), but Dall (1889a) indicated the depth as 175–450 fathoms (= 320–823 m). Accordingly, the coordinates cited here for the lectotype follow the MCZ Invertebrate Zoology online database (https://mcz.harvard.edu/invertebrate-zoology-research-collection), but not those provided by Rolán & Fernández-Garcés (2008), with a wrong latitude. Rolán & Fernández-Garcés (2008) did not provide the depth for the lots ANSP 368279 ( Bahamas) and ANSP 312592 (Florida Keys), but the online database of the respective collection (http://clade.ansp.org/malacology/collections/) indicates respectively 500 m and 183 m (here followed). The broad depth range (73–1040 m) provided by Rosenberg et al. (2009) is partly erroneous, because the depth of 1040 m was based on Rios (1985, 1994, 2009), i.e., a wrong identification for shells from Brazil; the shallowest record is based on the depth range (73–402 m) which Abbott (1974) provided for this species from West Florida, and it requires confirmation because the material was not figured.

Anatomic features of “ I.” longissima are herein studied for the first time. The species has welldeveloped eyes ( Fig. 2C ), considerably larger than those of Strobiligera species from deeper waters ( Fig. 18B ), suggesting that “ I.” longissima is not confined to waters with a complete absence of light. The operculum with a subcentral nucleus and the radula with many, weakly differentiated comb-like teeth (but marginal teeth considerably reduced) perfectly match with the current concept of Monophorus Grillo, 1877 ( Fernandes & Pimenta 2019b). However, an ongoing molecular phylogeny of Triphoroidea (in prep.) has raised suspicion about the monophyly of Monophorus , and the generic position of “ I.” longissima will be discussed further.

Geographic distribution

USA: Florida ( Dall 1889b; Abbott 1974; Rolán & Fernández-Garcés 2008), Louisiana ( Garcia & Lee 2002, 2020); Bahamas ( Rolán & Fernández-Garcés 2008); Cuba ( Dall 1889a, 1889b); Guadeloupe ( Lamy & Pointier 2018; this study); Martinique ( Lamy & Pointier 2018 – as Inella triserialis ).

Bathymetric distribution

Empty shells previously known from 73–823 m ( Dall 1889b; Abbott 1974). This study: 100–482 m (empty shells), 100–402 m (live specimens).

Figures

Fig. 2. “Inella” longissima (Dall, 1881). A–C. MNHN-IM-2019-20012, stn DW4555, 10.6 mm. D–G. MNHN, stn DW4555, 13.4 mm, 10.5 mm. H–M. MNHN, stn DW4549, 14.7 mm, 13.6 mm, 8.7 mm. Scale bars: A, C–D, F, H, J, L = 1 mm; B, E, G, I, K, M = 500 µm.

Fig. 3. “Inella” longissima (Dall, 1881). A–D. MNHN, stn DW4549, 11.9 mm, 11.2 mm. E–F. MNHN, stn DW4613, 20.1 mm. G–J. MNHN, stn DW4550, 10.0 mm, 10.5 mm. K–L. MNHN, stn DW4572, 19.0 mm. Scale bars: A, C, E, G, I, K = 1 mm; B, D, F, H, J, L = 500 µm.

Fig. 4. “Inella” longissima (Dall, 1881). A–D. MNHN, stn DW4613, 12.8 mm, 10.8 mm. E–F. MNHN, stn DW4615, 11.2 mm. G–H. MNHN, stn DW4637, 16.0 mm. I–J. MNHN, stn DW4549 (same shell as Fig. 2H). Scale bars: A, C, E, G, I–J = 1 mm; B, D, F, H = 500 µm.

Fig. 5. “Inella” longissima (Dall, 1881), MNHN-IM-2019-20012, stn DW4555. A. Outer jaw. B, D–F. Radula. C. Operculum. Minor letters indicate central (C), lateral (L) and first marginal (M1) teeth. Scale bars: A = 20 µm; B, D = 5 µm; C = 100 µm; E–F = 10 µm.

Fig. 18. Strobiligera cf. ibex (Dall, 1881), MNHN-IM-2013-61225, stn CP4618, 33.3 mm. Scale bars: A = 1 cm; B–F = 1 mm; G = 500 µm.