IUCN threat status:

Endangered (EN)

Comprehensive Description

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Description of Ba humbugi

This is what the original description by Solem 1982 as supplied by the wondrous Biodiversity Heritage Library says:

 

 

 

 

 Diagnosis. Shell of slightly less than average size, diameter 2.30-3.32 mm. (mean 2.72 mm.), with 3.125-3.5 tightly coiled whorls. Apex and spire strongly and evenly elevated, body whorl descending more rapidly, spire protrusion one-third to one-half body whorl width, H/D ratio 0.752-0.842 (mean 0.801). Apical sculpture of 11-13 (mean 12.0) high and prominent spiral cords. Postnuclear sculpture of irregular growth wrinkles and an occasional identifiable major rib with intergradation between these extremes. Microsculpture obscured by surface irregularities, visible in some areas as consisting of fine radial riblets, finer and more crowded spiral riblets, plus low and broadly rounded, much larger secondary spiral cords. Umbilicus either imperforate (25%) or with a small lateral crack (75%), possibly latter developing in adult stage only, since smallest example had closed umbilicus. Sutures deep except near end of body whorl, aperture and body whorl flattened laterally above periphery, inclined about 25  from shell axis.   Ba humbugi is immediately recognizable by its very high spire, low whorl count, reduced radial rib-  bing, and closed or laterally cracked umbilicus. Other Polynesian species with closed or nearly closed umbilici include the Samoan S. clausa and S. clista and the Lau Archipelago S. adposita. These species all have prominent radial ribbing and higher whorl counts. The Lord Howe Island Mystivagor  mastersi (Brazier, 1872) is similar in shape and whorl count but has vastly different sculpture and anatomy.  

 

 Description. Shell rather small, with 3.5 relatively tightly coiled whorls. Apex and spire markedly and evenly elevated, body whorl descending more rapidly, H/D ratio 0.810. Apical whorls 1.5, sculpture of 11 very prominent spiral cords. Postnuclear whorls with very irregular growth wrinkles and occasional major ribs with high periostracal extensions. Microsculpture a lattice of fine radial and  finer spiral riblets, irregular in spacing, crossed by more prominent spiral cords. Sutures deep, whorls flatly rounded above, evenly rounded below periphery. Umbilicus closed by expansion of basal lip  and tight coiling, with only a slight lateral chink visible. Color light reddish yellow with dark brown, almost black, periostracal extensions. Aperture ovate, flattened laterally above periphery, inclined  about 25 degrees from shell axis. Height of holotype 2.24 mm., diameter 2.76 mm.   Holotype. Fiji: Viti Levu, Station 122, Mt. Nangaranambulata at 2,700-3,200 ft. elevation. Collected  in dense forest by Yoshio Kondo on September 5, 1938. BPBM 178954.  

 

 Range. Interior of Viti Levu at 950-3,200 ft. elevation, Fiji.  

 

 Paratypes. Viti Levu: top of Mt. Korobamba (Station 60) at 1,000-1,300 ft. elevation (2 specimens,  BPBM 178758); Sanganakoreva area (Station VL-2, 1965), back of Tubarua saw mill, 950-1,000 ft. elevation, 5 miles inland from Ngaloa, Nuku District (1 specimen, FMNH 153605).   Remarks. The closed umbilicus, irregular ribbing, and very high spire of Ba humbugi immediately  separate it from any Pacific Island endodontid. In many respects, the shell recalls that of the New  Caledonian Rhytidopsis minutula. Until the latter can be dissected, the degree of relationship will remain uncertain. The Lord Howe Island species Mystivagor mastersi (Brazier, 1872) has gone further toward a succineiform shell. It differs in size (6 mm. diameter), strong color pattern, smooth shell surface, and apical sculpture of widely spaced radial ribs.   Spire angle varied greatly among the four specimens, with the one from Saganakoreva (FMNH  153605) having a much wider angle and lower H/D ratio (0.752). It was found under the same log as an example of Sinployea irregularis, so that the two species are unquestionably sympatric. Lack of any  black markings on the body probably indicates this is a strictly terrestrial species.  

 

 Dissection of two individuals showed major changes in the pallial systems that resulted in generic  recognition. Changes in the genitalia involved folding of the prostate-uterus, compaction and broadening of the albumen gland, shortening of the hermaphroditic duct, altering the simple clump insertion of the penial retractor into a complex, enfolding of the penis-epiphallus junction, and massive reduction of the penial pocket stimulator. Except for the latter change, these are adjustments to the whorl reduction and visceral hump compaction.   Comparison of penial structures in S. irregularis with those of Ba humbugi shows enlargement of the pocket stimulator in the first and reduction in the second.  

 

 A single sperm packet was taken from FNMH 153605, which was collected December 9, 1965, the morning after a shower ending a long drought.  

 

 Description of soft parts. Foot and tail equal in length to shell diameter. Sole undivided, bluntly rounded and slightly tapering posteriorly, truncated anteriorly. Pedal grooves very conspicuous, high on foot, uniting above tail, no caudal horn or middorsal groove developed. Slime network of large, rectangular sections on tail and sides of foot. Head retracted in all individuals examined. Gonopore position normal.  

 

 Body color yellow-white, no darker markings.   Mantle collar with thickened edge, no glandular extension onto pallial roof. Anus opening next to external ureteric pore , just inside pneumostome.   Pallial region extending half whorl apically. Lung roof clear, without granulations. Kidney about 1.58 mm. long, bilobed, deflected downward from parietal-palatal margin after 0.33 mm., lobes subequal, pericardial slightly longer than rectal, truncated anteriorly by ureter. Ureter compressed between kidney lobes, apical part curved downward around tip of kidney, no lung surface visible between kidney lobes. Heart two-thirds length of kidney, lying parallel to deflected plane of hindgut and parallel to lower edge of mantle collar. Principal pulmonary vein very short and inconspicuous, curving around edge of kidney. Hindgut deflected from parietal-palatal margin shortly after kidney apex, intestinal loop partly under heart.  

 

 Ovotestis occupying V-i whorl above stomach apex, a single, tightly compacted clump of palmately clavate acini with short collecting tubule. Hermaphroditic duct kinked initially, narrow, gradually tapering to past middle, grossly expanded, then sharply constricting before reflexing up to talon. Albumen gland (GG) with highly irregular surface, proportionately large, acini relatively small. Talon with globular head, short neck to carrefour, both buried in albumen gland. Prostate with a few long acini inserting onto side of uterus, which is bifolded. Uterus bipartite, folded upon itself, lower chamber enlarged and with thick, glandular walls.   Vas deferens with thick, glandular walls to penioviducal angle, narrowed abruptly and a thin-walled tube to epiphallus, loosely bound to penioviducal angle. Epiphallus two-thirds length of penis, head bulbous, internally with Y valve and longitudinal pilasters. Folded against head of penis at point of insertion. Penial retractor (PR) arising from diaphragm, about Mi length of penis, inserting in a broad fan around epiphallus and head of penis, with separate strands to penis apex and inner wall of epiphallus. Penis club-shaped, about 1.8 mm. long, tapering gradually to atrium, internally with a bulbous vergic papilla, greatly enlarged circular muscle band, and tiny stimulatory pocket pilaster. Lower portion with weak glandular ridges into atrium. Atrium short, without unusual features.   Free oviduct only slightly longer than vagina, equal in diameter to penis at midsection, internally with typical circular pilaster at spermathecal junction. Spermatheca with expanded head next to albumen gland, slender shaft next to prostate, base section abruptly expanding at base of uterus, internally with typical glandular pilaster and a larger sperm packet . Vagina (V) thin-walled, same diameter as free oviduct, internally with weak glandular pilasters.  

 

 Free muscle system typical, somewhat shortened. Right ommatophoral retractor passing through penioviducal angle, right rhinophoral retractor uniting before tail fan junction.  

 

 Stomach occupying seven-eighths of a whorl, starting one sixteenth of a whorl above pallial cavity apex. Intestinal looping compacted into narrow zone and protruding partly into pallial cavity area. Hindgut deflected from parietal-palatal margin for half of length, reaching margin near anterior end of kidney.  

 

 Digestive glands extending past ovotestis to apex, mainly along stomach, only one strand near albumen gland. Salivary glands short, not uniting above esophagus.  

 

 (Based on FMNH 153605 and BPBM 178954, 2 adult specimens.)  

 

 

 The OCR is suspect in places and this description should be checked against an original.     

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David

Source: BioPedia

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