Conus consobrinus

Conus consobrinus consobrinus (Sowerby I, 1850)

Conus consobrinus toroensis (Olsson, 1922)

Conus consobrinus ultimus (Pilsbry & Johnson, 1917)

Conus lavillei (Cossmann, 1913)

Conus scaliae (Bose, 1906)

Descrizione e caratteristiche ⁽⁴⁾:

Of medium size, elongate, moderately wide at shoulder. Shoulder sharply angulated. Anal fasciole slightly sloping, producing an almost square shoulder. Spire high and its profile almost smoothly conical, or moderately high and its profile slightly concave. Protoconch and earliest post-protoconch whorls missing. Shoulder of all except last, or last two, spire whorls strongly tuberculate; tubercles gradually disappearing. Anal fasciole concave, bearing faint or distinct spiral threads. Lower part of body whorl weakly sculptured; Height 61,7 mm., diameter 30,3 mm. ⁽⁴⁾.

Conus consobrinus consobrinus has a meager representation in the Gatun formation: two specimens from the lower part, two from the middle part, and one from the upper part in the western area ⁽⁴⁾.

Cossmann's Conus lavillei, collected along the canal at Mindi, where the upper part crops out, is identified as an exceptionally slender, immature specimen of this form ⁽⁴⁾.

The two shells from the lower part, one of which is shown on plate 56, figures 3, 7, and one from a horizon near the base of the middle part are relatively low- spired: an exceptional feature ⁽⁴⁾.

The large shell from the middle part in the western area ( pl . 56, fig . 9 ) is the only one that is fully mature. Its spire is somewhat worn ⁽⁴⁾.

Gatun specimens are almost square-shouldered, as are most others from mainland localities. Those from Jamaica are round-shouldered and so are most of those from the Dominican Republic ⁽⁴⁾.

Bose's illustration of the Mexican C. scaliae ( Böse, 1906, p. 51 , pl . 5 , figs. 41 , 42 ) suggests an immature C. consobrinus. His type (height 15.2 mm ), however, lacks spiral sculpture on the anal fasciole ⁽⁴⁾.

That C. consobrinus consobrinus is found in deposits of middle Miocene age in the Tehuantepec area is shown by Perillat Montoya's illustration and by a specimen in the collections of the U. S. National Museum ( USGS 10346 ). The high, or moderately high, strongly tuberculate spire is a diagnostic feature of C. consobrinus. The type material ( lectotype ) has been designated and illustrated recently by Pflug. The nominate subspecies occurs in deposits of middle Miocene age ⁽⁴⁾.

The lineage is continued by an almost square-shouldered form that has a tuberculate shoulder throughout, even on the body whorl of specimens that have a height of 50 mm . This form is C. consobrinus ultimus Pilsbry and Johnson ( Pilsbry, 1922, p. 330, pl. 20, fig . 8 ). It first appears in the late Miocene Limón formation of southeastern Costa Rica and continues in the Pliocene Moín formation of that area ⁽⁴⁾.

Conus consobrinus

IGM 794

Conus consobrinus

PRI ollection

Conus consobrinus toroensis (Olsson, 1922)

Shell of medium size, with a conic spire a little more than ½ the length of the aperture; the whorls of the spire numbering 12 plus are flat or slightly above the suture; this carina on all except the last whorl bears low nodes, about 20 to the later whorls; the spire-whorls are otherwise smooth except for the arcuate growth lines; the last whorl is a tapering cone, nearly smooth, except for the faint spirals about its lower one-third; the aperture id narrow, straight, with a thin arcuate outer lip.

Height 45 mm., diameter 21 mm., aperture 33 mm.

This shell belong to the Conus consobrinus group, agreeing in its form and strongly nodulated spire whorls. The main difference is that toroensis is nearly smooth, the spirals showing only on the lower one-third, while consobrinus has most of the last whorl covered with beaded spirls ⁽⁶⁾.

Conus toroensis (Olsson, 1922)

Pl. 2 fig. 7

Conus toroensis (Olsson, 1922)

Middle Miocene

C. torensis Olsson ( 1922, p. 48, pl. 2, fig. 7 ) may be treated as a weakly sculptured late Miocene subspecies ⁽⁴⁾.

C. emersoni Hanna ( 1963, p. 25, pl. 1 , fig. 2 ), dredged off Cape San Lucas, Baja California, is probably a descendant of C. consobrinus. It is round shouldered and lacks tubercles on the shoulder of the body whorl , and therefore is similar to C. consobrinus consobrinus ⁽⁴⁾.

Occurrence:

Lower, middle, and upper parts of Gatun formation (middle Miocene). Lower part, locality 138c. Middle part, eastern area, locality 139d ; western area, locality 161b. Upper part, eastern area, Cossmann's record ; western area , locality 185. Middle Miocene deposits, Darién area ( small race , USGS 8430, 8477 ) , Panamá.

Agueguexquite formation ( middle Miocene ), Tehuantepec area , México.

Bowden formation ( middle Miocene ) Jamaica. Gurabo formation (middle Miocene ), Dominican Republic.

The high straightly conic spire with coronate whorls is distinctive. In large specimens from one to two, or rarely three, latest whorls are without nodes. Spiral sculpture of the last whorl isvariable and in adults generally restricted to the lower half. In some young specimens the last whorl is covered with spiral threads, partly granose. The posterior sinus of the aperture is very deep. There is a large series of various ages in the Gabb collection. Also found in the Bowden formation, and in a modified form it existed into the Pliocene ⁽³⁾.


Conus consobrinus Lectotype BMNH G83962 mm. 61,7 x 30,3 Miocene – Santo Domingo

Conus consobrinus ⁽³⁾

Conus consobrinus ⁽⁴⁾ The two shells from the lower part, one of which is shown on plate 56, figures 3, 7, and one from a horizon near the base of the middle part are relatively low-spired: an exceptional feature. The large shell from the middle part in the western area ( pl . 56, fig . 9 ) is the only one that is fully mature. Its spire is somewhat worn.

Conus lavillei (Cossmann, 1913) ⁽⁴⁾ mm. 37 x 14 Miocene – Mindi (Canal zone) – Panama

Conus scaliae Syntype IGM 145 Miocene Oaxaca - Messico	Conus scaliae (Bose, 1906) mm. 15,2

Conus toroensis (Olsson, 1922) Pl. 2 fig. 7	Conus emersoni ⁽⁷⁾ Figure§ 1-7. Conus emersoni Hanna, 1963 ----------------- Figures 1-3. Type material dredged off Los Frailes, Baja California, depth 549 m. 1. Holotype, AMNH 105211, length 43 mm, faded, dead-collected specimen, lacking periostracum. 2, 3. Paratype, CAS 12405, length 49.0 mm, subfossil specimen (surface gray), showing naticid bore hole. --------------------- Figures 4-7. Newly reported specimens dredged off Isla Santa Maria (Floreana), Galapagos Islands, Ecuador, depth 310 m. 4. AMNH 248261, length 46.2 mm, dead-collected specimen. 5. LACM 146906a, length 33.3 mm, live-collected specimen with periostracum intact. This specimen was used for opercular and radular illustration. 6. 7. LACM 146906b, length 34 mm, dead-collected specimen with periostracum removed to show color pattern.

Conus consobrinus ultimus (Pilsbry & Johnson, 1917)

Shell more squarely shouldered then C. Consobrinus, and with tubercles extending upon the angle of the last whorl.

Costa Rica. Pliocene.