Syntomodrillia lissotropis (Dall, 1881)

Fallon, Phillip J., 2016, Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species, Zootaxa 4090 (1), pp. 1-363: 332-335

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http://doi.org/10.11646/zootaxa.4090.1.1

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scientific name

Syntomodrillia lissotropis (Dall, 1881)
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Syntomodrillia lissotropis (Dall, 1881) 

( Plate 172View PLATE 172, Figs. 1–6View Fig. 1)

Pleurotoma (Mangilia) lissotropis Dall  , August 1881: 58–59, [not illustrated].

Daphnella (Raphitoma) lissotropis (Dall, 1881)  : Tryon (1884: 312 [list]).

Daphnella lissotropis (Dall, 1881)  : Patel (1888: 92 [list]).

Drillia lissotropis (Dall, 1881)  : Dall (1889 a: 91, pl. 11, figs. 3, 4): Dall (1889 b: 98, pl. 11, figs. 3, 4); Dall (1890: 37); Dall (1896: 21 [Pourtalès Plateau, Florida Keys, list]); Maury (1922: 36 [list]). Note: The specimen depicted in Dall (1889: pl. 11, fig. 4) and the lot referred to by Dall (1896) have both been lost and cannot be confirmed as this species.

Syntomodrillia lissotropis (Dall, 1881)  : Woodring (1928: 160 [type of genus]); Bartsch (1934: 25–26); Fargo (1953: 370 [as type of genus]); Radwin (1969: 232); Woodring (1970: 388 – 89 [reaffirmation as type of the genus]).

Cymatosyrinx lissotropis (Dall, 1881)  : Johnson, C.W. (1934: 136 [list]).

Splendrillia (Syntomodrillia) lissotropis (Dall, 1881)  : Powell (1966: 84, pl. 12, fig. 20 [reproduction of Dall’s 1889 a, pl. 11, fig. 4]); Abbott (1974: 275, fig. 3105 [also Dall’s 1889 a, pl. 11, fig. 4]).

Splendrillia lissotropis (Dall, 1881)  : Turgeon et al. (1988: 100 [list]); Turgeon et al. (1998: 102 [list]); Rosenberg et al. (2009: 665 [list]).

Not this species, or unconfirmed, extralimital and fossil reports.

Pleurotoma (Mangelia) hypsela Watson  , October 1881: 433, may be a synonym according to Dall (1889 a: 91); listed as a synonym in Dall (1890: 36). The type locality is off Pernambuco State, Brazil; the holotype is in NHMUK 1887.2. 9.1058. The holotype is in very poor condition but is unlikely to be the same species because of differences in gross morphological features such as rib form and shell profile.

Drillia (Drillia) lissotropis  var. scissurata Dall, 1890: 36–37  [fossil]. Type locality: Caloosahatchie beds, Florida. Du-Bar (1962: 39); Powell (1966: 84 [list])

Drillia lissotropis (Dall, 1881)  : Dall & Simpson (1901: 387 [ Puerto Rico; poss. = Syntomodrillia portoricana  , new name]); Warmke & Abbott (1961: 140 [list; from Dall & Simpson, 1901]).

Drillia lissotropis  var. dorsuosa Pilsbry & Johnson, 1917: 157  [fossil]. Type locality: Santo Domingo Oligocene. Pilsbry (1922: 321, pl. 18, fig. 5).

Splendrillia lissotropis (Dall, 1881)  : Radwin (1969: 232 [list; Panama]); Gracia et al. (2004: 64, fig. 47 [ Colombia]); Daccarett & Bossio (2011: 130, fig. 798 [ Colombia]); Williams (2005; 2006; 2009: 1587 [illustrations not S. lissotropis  ]).

Splendrillia (Syntomodrillia) lissotropis (Dall, 1881)  : Sander & Lalli (1982: 317 [ Barbados]); Rios (1983 [ Brazil]); Rios (1985: 140, pl. 48, fig. 645 [ Brazil]); Rios (1994: 163; pl. 54, fig. 737 [ Brazil]).

Cerodrillia lissotropis (Dall, 1881)  : Kaicher (1984: card 3966 [photo & ANSP 344376 not of S. lissotropis  ]).

Type material. Two specimens, 4.5 x 1.85 & 5.5 x 2.1 mm, were in MCZ 7075, one from R/V Blake Sta. 20 (off Bahia Honda) and the other from R/V Blake Sta. 2 (off Morro Light, Havana), according to the MCZ register entry recorded by A. Kabat in 1995. Although noted in the register as syntypes, Dall does not mention the Sta. 2 specimen (the larger of the two) in either his original 1881 or emended description in 1889, and furthermore, it is not customary to place specimens from different sampling stations in the same lot, so it may have been added at a later date. It has since been moved to MCZ 383693. The 4.5 mm specimen fits Dall’s 1881 original description and agrees with the stated length. Although Dall did not identify it as type, the specimen is referred to as the type of Pleurotoma (Mangilia) lissotropis  (height 4.5 mm; Dall, 1889, pl. 11, fig. 3) by Woodring (1970: 388 – 89), which satisfies the requirements of a lectotype designation (ICZN 2000 Article 74.6). In addition, the specimen in MCZ 7084, also from R/V Blake station 20, but labeled “ Pleurotoma (Drillia) Verrillii  ” may possibly be this species, a paralectotype, but was out on loan and not examined closely.

Drillia lissotropis  was first illustrated in Dall (1889 a), along with a 7.0 mm specimen from Blake Sta. 134, off St. Croix. Dall also emended its description in 1889 thusly: “The curvature and number of the ribs vary slightly, and the spaces between are indifferently perfectly smooth, or finely spirally striate, especially toward the anterior end of the shell.” He listed five additional lots from the Blake collections as this species, which appear in the table below. The original lot and the five subsequent ones are all then taken as part of the type series (ICZN 2000 72.4.1).

After careful examination of most of the specimens in these latter five lots (some are lost), none match the lectotype. Therefore the 4.5 mm specimen in MCZ 7075 is the only representative of the taxon among all six lots. The examined specimens in the five other lots, and the 5.5 mm specimen in MCZ 383693, are believed to either be S. woodringi  or other, undescribed species, two of which are described for the first time in this work.

273 103 [188] near Barbados MCZ 7077 (6) S. woodringi  (4)

USNM 87477 (2) orig. 9 unidentifable (1) USNM 87477 a (2) S. flavopunctata  , n. sp. (1) USNM 87477 b (2) S. woodringi  (2)

USNM 87477 c (1) S. woodringi  (2)

USNM no#-dropped spec. with S. harasewychi  , n. sp. (2) Dall’s lissotropis  acc. to S. woodringi  holotype Woodring (2?) No S. lissotropis  present. 282 154 [282] off Barbados USNM 87478 (5) Unidentifiable fragments 290 73 [134] off Barbados USNM 87476 (1) not examined

Three of the four specimens in MCZ 7076 belong in Syntomodrillia  but are not the same as S. lissotropis  and are presently undescribed (Pl. 172, Figs. 12–14); the fourth is missing. These specimens are larger, with stronger spirals, a smaller protoconch, and round, not angled shoulders as exhibited by S. lissotropis  . Size of the three are: 7.7 x 2.8, 8.4 x 3.2 & 7.8 x 3.0 mm.

The specimen in MCZ 7078 was the model for the drawing of an “adult D. lissotropis  ” in Dall (1889 a: fig. 4) but its identity could not be confirmed because it is missing from its tray (in May 2014 visit). The drawing is not detailed enough to distinguish it from other species of Syntomodrillia  or from similar-looking species of Lissodrillia  (no spiral grooves are shown on the anterior fasciole, a characteristic of Lissodrillia  ).

None of the six specimens in MCZ 7077 from off Barbados are S. lissotropis  . Four are S. woodringi Bartsch, 1934  and are treated in the section on that species, one is unidentifiable, and the last a very poor specimen of Splendrillia flavopunctata  , new species (described earlier in this work).

USNM 87477 originally had nine specimens, according to the lot register. It appears that Bartsch separated these into three additional lots, his selection of the holotype of S. woodringi Bartsch, 1934  being given the lot number USNM 87477 c. The four lots together do not add up to nine specimens, but two may be in the vial of 11 specimens (five species) recovered from trays dropped by Woodring. He noted on a slip in the vial that it contained some of Dall’s lissotropis  but not the type. The two specimens that remain in the original lot, USNM 87477, are both S. woodringi  (Pl. 172, Figs. 9–10), as are the two specimens in Bartsch’s USNM 87477 a (Pl. 172, Figs. 7–8). The two specimens in USNM 87477 b are S. harasewychi  , new species (Pl. 169, Figs. 9–10). Of the remaining two lots from off Barbados, USNM 87478 has five not readily identifiable fragments, which are not figured, and the single specimen in USNM 87476 was not examined.

Dall (1896: 21) lists an additional lot from Pourtalès Plateau, Florida Keys, in 200 fms [366 m], stating that they were “the first specimens obtained since the original types.” These specimens (USNM 107485) have been missing since 3 Feb 1967 (note on slip in vial).

In summary, none of the examined Barbadian specimens agree with the description and characteristics of S. lissotropis  . They differ in whorl profile, protoconch sizes, and total shell length. Although not examined, it is considered unlikely that the specimen in USNM 87476 is the same as the type.

Type locality. R/V Blake Station 20, off Bahia Honda [Artemisa Prov.], Cuba, 23 ° 2 ′ 30 ″N, 83 ° 11 ′00″W, in 220 fms [402 m].

Other material examined. An additional six specimens were examined: 3.7 x 1.6, 3.5 x 1.6, 3.5 x 1.6, 2.8 x 1.4, 2.8 x 1.4, & 2.9 x 1.5 mm, in 465 m, Wood Cay, Grand Bahama I., 26 ° 44 ' 15 "N, 079° 58 ' 15 "W, T. Askew! ex Worsfold coll. (ANSP 369552). This lot and the type are from bathyal depths in the Straits of Florida, the specimens are about the same size as S. lissotropis  ( Plate 172View PLATE 172, Figs. 3–6), and includes mature and juvenile specimens.

Range and habitat. Florida Straits (off Cuba; off Grand Bahama I., Bahama Is.). Reported from bathyal depths of 402 and 465 m.

Description. Shell very small (4.5 mm in total length), broadly fusiform with a blunt-tipped spire; whorls number to about 6 ¼, the last approximately 60 % of the total length, suture appressed; aperture short and relatively wide. Protoconch of 2 translucent, relatively large, smooth round whorls, the first partially immersed in the second such that the apex appears dome-shaped. Axial sculpture of broad, low, widely spaced, shouldered ribs that run from suture-to-suture but evanesce at anterior fasciole on last whorl, number 9 on penultimate and 6 on last whorl; whorl peripheries at about mid-whorl, slightly angled giving the whorl a shouldered appearance. Varix like a swollen rib, about ⅓-turn from edge of outer lip. Spiral sculpture of about 5 ridges on the anterior fasciole. Microsculpture of very faint, almost imperceptible spiral grooves between ribs on last whorl (see Plate 172View PLATE 172, Fig. 6). Sulcus with evanescent ribs, lower approaching then obsolete at suture. Outer lip mostly missing on type. Anal sinus missing on type. Inner lip recumbent, emarginated, with a weak parietal lobe at side of anal sinus. Anterior canal short, possibly shortened by wear on the type, without a notch; anterior fasciole not swollen. Color opaque white “shining with the lustre of paraffine”. The type has probably been discolored by age.

Remarks. Taxonomy. In 1889 Dall emended his original description S. lissotropis  with the observation that the species was “indifferently smooth, or finely spirally striate, especially toward the anterior end of the shell.” Dall (1889 a: 91–92). Spirals are barely perceptible on the surface of the lectotype, but under the right lighting and magnification a few are observable, so it is understandable that the spirals were initially overlooked in the 1881 description. Additionally, Dall believed his 4.5 mm type to be a juvenile specimen, subsequently illustrating a larger, 7 mm “adult” from St. Croix in his 1889 revision. The 4.5 mm type now lacks its original gloss (originally described as “shining with the lustre of paraffine”) with the outer lip, anal sinus and portion of the anterior canal broken off; however, its total length of 4.5 mm is probably close to its maximum adult size. A weak parietal callus, and varix is present just before the break, which suggest that the shell is an adult, not juvenile specimen.

Syntomodrillia lissotropis  is the type of the genus with the diagnostic characters of the genus being a very small, glossy shell, ribs from suture-to-suture, spirals on the anterior fasciole and weak intercostal spirals. It is unique for its relatively large protoconch, short profile (very short anterior canal and few and slightly angled whorls a little below the suture. Identification. Syntomodrillia lissotropis  has historically been confused with S. woodringi Bartsch, 1934  , which is larger, possesses stronger intercostal spirals, generally less inflated whorls with peripheries at mid-whorl, not below, and round shoulders not angled ones as in S. lissotropis  . Most of the specimens examined from Dall’s Barbados type lots are larger, have strong intercostal spirals, have whorl peripheries mid-whorl, and are believed to be conspecific with Bartsch’s S. woodringi  . An unnamed species from off the north coast of Cuba is similarly larger, with a different whorl profile, longer anterior canals, rounded, not angled whorls, and stronger spiral grooves (Pl. 172, Figs. 12–14). Syntomodrillia lissotropis  is also similar to S. carolinae Bartsch, 1934  and S. portoricana  , new name. It differs from both in possessing angled whorls, a shorter anterior canal, a rounder body whorl, and in possessing only weak spirals. The whorls are more evenly convex in S. carolinae  and in S. portoricana  .