Helminthoglypta (Charodotes) morroensis ( Hemphill, 1911 )

Roth, Barry & Tupen, Jeff, 2004, Revision of the systematic status of Helminthoglypta walkeriana morroensis (Hemphill, 1911) (Gastropoda: Pulmonata), Zootaxa 616, pp. 1-23 : 18-21

Helminthoglypta (Charodotes) morroensis ( Hemphill, 1911)

( Figures 5–8 )

Helix var. morroensis Hemphill 1911:103 .

Helminthoglypta (Helminthoglypta) walkeriana (Hemphill) , in part, Pilsbry 1939:128 –129.

Helminthoglypta walkeriana morroensis (Hemphill) , Wilcox 1950a:2 (as " morrosensis "). — Wilcox 1950b:23. — Smith 1970:41. — Roth 1973:149 –153.

Helminthoglypta (Helminthoglypta) walkeriana morroensis (Hemphill) , Coan and Roth 1987:331.

Helminthoglypta (Charodotes) walkeriana morroensis (Hemphill) , Roth and Sadeghian 2003:25.

Type material: Syntypes CAS 0 58820 (11), SBMNH 33934 (6), UCM 20179 (4), USNM 174683 (2), USNM 17684 (2) ( Roth and Sadeghian 2003).

Diagnosis: Charodotes with moderately large, depressed­helicoid shell, papillation strong, in roughly collabral trend; most papillae longer in axial dimension than spiral; incised spiral grooves weak or absent; penis cylindrical, of about same diameter as epiphallus, not markedly thin­walled, with 7–10 anastomosing, crenulated pilasters, grading into inner chamber of epiphallus without interruption.

Description: Adult shell height 10.5–17.4 mm, diameter 15.7–25.3 mm; height 62– 73% of diameter. Shell solid, depressed­helicoid, with 4.8–6.0 whorls; coiling tightness (number of whorls divided by natural logarithm of shell diameter) 1.7–1.9. Spire lowdomed; suture moderately to strongly impressed, whorls somewhat flattened. Periphery broadly rounded. Embryonic whorls 1.5–1.6. Post­embryonic sculpture of convex­forward collabral rugae, and strong papillation over entire surface including base of body whorl and umbilicus. Papillae aligning with a roughly collabral trend; most longer in axial dimension than spiral. Incised spiral grooves usually absent or only weakly evident on shoulder of body whorl; rarely clearly evident or strong. Body whorl inflated, last one third­ to one quarter­turn gently descending. Base tumid; umbilicus contained 11.5–12.2 times in diameter, 20–100% covered by inner lip. Aperture broadly ear­shaped; lip narrowly turned outward, not strongly thickened. Shell pinkish tan under a medium to dark brown periostracum when fresh, weathering to tan, then white; aperture interior of fresh shells purplish; lip purplish tan to white. Luster matte to silky, glossy on base.

Skin of animal blackish in life; in alcohol gray, grading to cream color on body stalk; lighter mid­dorsal row of tubercles present or absent. Sole of foot pale grayish tan or cream­colored, sometimes darker and grayer along margins. External genital pore a prominent vertical slit with white border. Mantle collar pale cream­colored, grading to light purplish gray at edge, with three prominent lappets. Mantle over lung clear buff, with about 40–60% of surface covered by network of black pigment, densest mid­dorsally, sparse in umbilical area.

Mucous membrane envelope enclosing much of lower genitalia. Dart sac spherical. Common duct of mucus bulbs robust. Atrium short; atrial sac massive, roughly conical. Vagina short, less than half length of free oviduct. Spermathecal duct diverticulum long, capacious, almost twice diameter of spermathecal duct, with longitudinal pilasters and ridges internally. Spermatheca spherical or teardrop­shaped.

Epiphallic caecum very long and slender, convoluted in lower portion. Penial retractor muscle strap­like, inserting variably on medial crook in epiphallus. Epiphallus cylindrical for most of its length; lower, double­walled section is about 40 percent of total length; internal tube of double­walled section mostly cylindrical, slightly expanded near middle, with 5–10 longitudinal, anastomosing, crenulated pilasters internally. Penis about 5 mm long, cylindrical, of about same diameter as epiphallus, broadening slightly above insertion on atrium. Walls of penial sac not markedly thin, internally bearing 7–10 longitudinal, anastomosing, crenulated pilasters, grading into inner chamber of lower, double­walled section of epiphallus without interruption.

Comparisons: Helminthoglypta morroensis differs from H. walkeriana ( Figures 9­ 12 ) as documented in the main body of results of this study. In terms of characters most useful for ready identification, H. walkeriana has a more globose, usually more tightly coiling shell (coiling tightness 1.8–2.1) with more whorls at maturity. The adult shell height of H. walkeriana is 73–87% of the diameter. The umbilicus is contained 12­18 times in the shell diameter. The post­embryonic sculpture consists of irregular collabral rugae, most of them cut into elongated granules by spiral grooves, especially on the shoul­ der of the penult and body whorl ( Figure 9 ). Papillation ranges from absent to clearly evident, but is most commonly absent or visible only with close inspection. Even in fully adult shells, the outer lip is often very narrowly turned outward. As noted above, the skin of H. walkeriana is lighter colored, the mantle over the lung is less extensively covered by dark pigment, and the penis is slender, hourglass­shaped, with simple, smooth pilasters rather than the crenulated, anastomosing pilasters of H. morroensis . Helminthoglypta morroensis lacks any tongue­like protuberance or other structure at the junction of penial sac and epiphallus.

Helminthoglypta (Charodotes) fieldi , which occurs farther south in San Luis Obispo and Santa Barbara Counties, from Pismo Beach to Surf, mainly along the coast ( Roth 1973), differs from H. morroensis in having a broadly conic spire and papillae generally absent from body whorl except behind the outer lip and in the umbilicus.

Helminthoglypta (Charodotes) reediana Willett, 1932 , which in San Luis Obispo County occurs from Lowe and Ranchito canyons in the northern part of the county to Chalk Mountain, near Atascadero, differs from H. morroensis in having a complex sculpture of incised spiral grooves, low, smooth collabral rugae, and dense, irregularly shaped papillae over entire surface. The papillae are spirally elongated, in spiral trends on the spire, more irregular in shape and spacing on the penult and body whorl. Black spots cover about 60% of the surface of the mantle over the lung. The atrial sac bears a distinctive glandular collar below the dart sac.

Vernacular name: For purposes of the American Fisheries Society list of the common names of mollusks ( Turgeon et al. 1998) and other administrative uses, we propose the name "Chorro shoulderband" for H. morroensis , with reference to Chorro Valley, a major component of its geographic range.

Figures

FIGURES 5 – 12. Shells of Helminthoglypta morroensis and H. walkeriana. Figures 5 – 8. Helminthoglypta morroensis, BR 2571, Highway 1 at Stenner Road, San Luis Obispo; top, side, and basal views of shell and detail of papillose sculpture (scored as Ppl = 3, see Methods section) on shoulder of penultimate and body whorls. Shell diameter 23.1 mm. Figures 9 – 12. Helminthoglypta walkeriana, BR 2568, Elfin Forest; detail of papillose sculpture (Ppl = 1) and spiral grooves (Grv = 2) on shoulder of penultimate and body whorls, top, side, and basal views of shell. Shell diameter 22.1 mm.