Kincaidiana hexatheca Altman, 1936

Fend, En. V., 2009, An evaluation of the genus Kincaidiana Altman, 1936, with the designation of Altmanella n. gen. (Annelida, Clitellata, Lumbriculidae), Zootaxa 2077, pp. 1-30 : 3-6

Kincaidiana hexatheca Altman, 1936

Figures 1–2

Material examined: type series. Washington: Pacific Co.: Loomis Lake , collected in 1931 or 1932, 6 dissected, slide mounted worms; sagittally sectioned worms II, IV, V, VI, VII, VIII, IX, XII, XIII; transverse sections X, XI, XIV. Collected by L.C. Altman .

Other material. California: Mendocino Co.: Inglenook Fen at MacKerricher State Park near Fort Bragg, 1-Jul-05. Oregon: Curry Co.: Rogue River at Quosatana Campground, 8-Jun-03. Douglas Co.: Cow Creek, 28-Apr-04. Unnamed cold spring, 7-Jun-03. Josephine Co.: Darlingtonia bog near O'Brien, 26-Oct-99. Illinois River near Sixmile Creek, 25-Oct-99. Lane Co.: Spring at mouth of Tenmile Creek, 1-May-99. Spring/ bog at Big Creek, 11-May-01. Marsh at base of Mt. Pisgah, near Eugene, 29-Jan-00. Multnomah Co.: Oneonta Creek, Columbia Gorge, 4-Jun-03. Tillamook Co.: small spring on Nestucca R. near Blaine, 4-Jun-03. Yamhill Co: Seep on east side of McGuire Reservoir near McMinnville, 4-Jun-03. Washington: Clallam Co.: pool along Bogachiel River on Undie Road, 26-Apr-04. Jefferson Co.: seeps along Hoh River Road, 29-Apr- 99. 26-Apr-04. Roadside ditch on Clearwater Road, near Hoh River, 3-Jun-03. Pacific Co.: Spring on Naselle River, 30-Apr-99. All collected by S. Fend.

Remarks. The emended diagnosis limits the genus to worms resembling K. hexatheca and its possible undescribed relatives, rather than the broadly inclusive definition given by Cook (1971). The original description of K. hexatheca is relatively complete, and new collections from additional sites confirm Altman’s (1936) observations, as well as the above diagnosis. The combination of a very elongate proboscis, unusual anterior chaetae, a forward shift of reproductive organs by one segment (see Brinkhurst [1989]), prosoporous male ducts, and the hexathecate condition with the first pair of spermathecae in the atrial segment easily distinguishes Kincaidiana from all other lumbriculid genera.

Additional reproductive characters distinguishing Kincaidiana include the penial and spermathecal morphology, the posterior location of the male funnels, and vasa deferentia with a partial muscle coat. The short, pendant penes are within eversible sacs, and these in turn are subtended by conical, possibly telescoping porophores ( Fig. 2G–H). The spermathecal ampullae are unusually elongate, with most of the sperm lined up along the epithelium, in an expansion near the ectal duct ( Figs. 1E, 2E–F); the large, thick spermathecal ducts are also unusual. The muscle layer extending onto the proximal part of the vas deferens ( Fig. 2I vs. 2J) was noted by Cook (1971); this character may have been overlooked in other lumbriculid descriptions, but otherwise has only been noted in Pilaridrilus Fend & Lenat. The (posterior) male funnels fold back into the sperm sacs in many lumbriculids, but the posterior displacement by one or more segments ( Fig. 1E) is unusual; it has, however, been illustrated for the Palearctic Guestphalinus wiardi ( Michaelsen, 1933) .

Internal somatic characters have generally not been emphasized in lumbriculid descriptions. Nephridia are difficult to observe, and thus poorly described in most lumbriculids; however, K. hexatheca nephridia have an unusual form and vertical orientation. The long, narrow postseptal expansion and duct typically follow a lateral blood vessel dorsally, similar to nephridia of Rhynchelmis Hoffmeister (cf. Fend & Brinkhurst 1989); the dorsal loop then usually extends posteriorad (ventromedially) before looping anteriad to the duct and nephropore ( Fig. 1D). Pre-clitellar nephridia were not observed in K. hexatheca ; instead, the first nephridia are on the first septum behind the female pores. This appears to be the most common arrangement in the Lumbriculidae , although due to the anterior shift in reproductive organs (sensu Brinkhurst 1989), they are on 11/12, rather than the usual 12/13. Highly branched blood vessels in posterior segments are not unusual in the larger lumbriculids, although the pattern may be distinctive at the genus or species level. Details of the vascular system are difficult to see in many preparations, but the new K. hexatheca material differs somewhat from the original description. In the new material, branched lateral vessels begin after about XX; one or two may be present at the dorsal vessel, with the anterior larger, and a branch terminates in the ventral vessel and/ or (more commonly) in the perivisceral sinus ( Fig. 1C). This arrangement differs slightly from other large, proboscis-bearing, Nearctic lumbriculids such as Eclipidrilus (Premnodrilus) Wassell or Rhynchelmis , in which branched lateral vessels (if present) are two pairs per segment, beginning near X ( Fend 2005, Fend & Brinkhurst 2000). Body wall musculature in K. hexatheca may also be unusual, pending more detailed descriptions of other genera: the circular muscle fibers are arranged in regular, transverse arches or cylinders in anterior segments ( Fig. 2C).

Many of these characters are likely to be apomorphic according to the analysis of Brinkhurst (1989), and some are unusual (although not unique) within the family. Although morphological details vary both within and among populations, in most cases there do not appear to be regional morphotypes that would indicate additional species. Additional details on K. hexatheca morphology and population differences, and a new species from northern California will be reported in a separate contribution.