Diplocardia farrishi Damoff & Carrera-Martínez, 2025

Damoff, George A. & Carrera-Martínez, Roberto, 2025, A review of literature and a reevaluation of Diplocardia verrucosa Ude, 1895 resulted in the discovery of a new species in southern New Mexico and west Texas, USA, Zootaxa 5589 (1), pp. 363-381 : 374-376

Diplocardia farrishi Damoff & Carrera-Martínez sp. nov.

urn:lsid:zoobank.org:act:12A34A02-93E9-4D4A-9D68-B74A6C29C3BB

Figure 2 D–F

Synonyms. Diplocardia verrucosa Gates, 1967 , 1977 (in part).

Material examined. Holotype: Clitellate , USNM 1742106 . White Oak Springs , Lincoln National Forest, Eddy County, New Mexico, USA (32˚14’40”N, 104˚43’23”W; elevation 1562 m). Collectors George A. Damoff and Michael A. Damoff on 22 March 2005. Site accessed by approximately 0.5 km hike from north terminus of side road off of Forest Service Road 525. Closed canopy of mixed hardwoods in deep narrow ravine with deep silt loam among boulders in the Chihuahuan Desert. Paratypes: 12. USNM 1742107–1742118 .

Etymology. Named in honor of Ken Farrish, the dissertation director of the first author, whose engaging manner during soil lectures was the providential means first used to direct his attention to the great need of earthworm ecology research. In the many years that have followed, Ken has continued to give much enthusiastic guidance, support, and encouragement. There is a slight regret that the specimens named in his honor lack semblance of colors to the Farrish tartan, but this deficiency may be overlooked if the species proves to enhance the flavor of the family haggis recipe.

Diagnosis. Small-sized, quadrithecal earthworm, 140 mm length X 3.4 mm diameter (xxx). Segment count 134. Epilobous tongue 1/2 width of segment, open, with minimal slight rugosities parallel to long axis of organism. Saddled-shaped clitellum, dorsal and ventral extent all of xiii–xix, with ventral margin slightly ventrad to a. No genital tumescences. Male groove narrow and shallow in 1/2xix─1/2xxi, nearly straight without secondary indentations associated with segmentation. Single dorsal blood vessel throughout. Last hearts xii. Intestinal origin xviii. Calciferous lamellae absent. Acryptate spermathecae with sessile quadruple-lobed diverticulum near base of ovoid ampulla.

Description

EXTERNAL.—Small-sized earthworm. Mean length, width, segment count and other character traits are in figure 2 and table 3.

Body shape generally cylindrical throughout. Widest at vi–ix, postclitellum diameter uniform nearly to last dozen segments where body on some specimens somewhat flattens. Biannulation begins around iv and transitions to triannulate around viii through xii, little or no annulation in clitellar segments xiii–xix, triannulation resumes at xx and continues through remaining segments, with the last half dozen or more absent of any annulation.

Pigmentation absent. Body color of formalin-fixed, ethanol-stored specimens (nearly 20 years) uniform throughout: brown (7.5YR 5/4), clitellum strong brown (7.5YR 5/8).

Epilobous tongue ca. 1/2 width of segment, with some isolated populations at divergent sites with a closed epilobous tongue and others open. One specimen tanylobous. Rugosae on peristomium slight and mostly parallel with the long axis.

First dorsal pore 6/7 or 7/8, no dorsal pores evident in clitellar segments, with dorsal pores evident in all postclitellar segments except last few. Nephridiopores inconspicuous at d.

Saddle-shaped clitellum xiii─xix filling all segments both dorsally and ventrally, though less thick in xiii and xix. Ventral margin of clitellum distinct, 0.1 mm within a–a, resulting in a distinct ventral 0.3 mm region absent of clitellar material extending all of xiii–xix. All setal pairs visible in all clitellar segments.

Setae begin ii, closely paired below mL line. Ambulatory setae, both pairs, conspicuous in all segments before periproct including viii, ix, xiv, xix, and xxi; only a and b of xx not observed. Holotype setal arrangement the same at x and xxx: aa: ab: bc: cd: dd = 4.4:1:3.2:1.2:17.6. Copulatory and penial setae are unmodified or absent.

Spermathecal pores in line with a, on anterior margins of viii, ix, both the same size (less than 0.1 mm in diameter), slightly raised (about 0.1 mm) on conical papillae (about 0.2 mm diameter) that extends anteriad about 0.1 mm over intersegmental furrow.

Ovipores in xiv, slightly within a–a (less than 0.1 mm) and midway between anterior margin and a. The pair of pores slightly raised on a single ovoid papilla (“halo”) that extends slightly lateral to a–a; similar strong brown color as clitellum.

Male groove, in line with a, extends from 1/2xix–1/2xxi, nearly straight to slightly crescentic without secondary indentations associated with intersegmental grooves or secondary annulations. Short (slightly greater than 1 mm length), shallow (less than 0.1 mm), narrow (greatest width less than 0.1 mm). Slight ridge entire circumference (about 0.1 mm height). Prostatic pores inconspicuous in tips of male groove. Male pore at anterior-most margin of xx within male groove.

Genital tumescences (GT) absent on all specimens examined.

Spermatophores. None observed adhering to the exterior body wall.

INTERNAL.—Septa thickened yet translucent 6/7─9/10, musculature not evident. All septa posterior to 12/13 same thickness. Many preclitellar septa drape anteriad covering internal organs in the adjacent anterior segment where septa attach to the body wall. Intersegmental bands extend posteriorly from the surface of the pharynx (ii–iv) and gizzards (v–vi). Slender transeptal muscle bundles (less than 0.1 mm diameter) extend posteriorly, with greatest abundance associated with the pharynx, penetrate septa at oblique angles. Anterior end attached to an organ of the alimentary canal and the posterior end attached to the body wall.

Coagulum (preserved coelomic fluids), not overly abundant in segments anterior to intestine. Body musculature gracile throughout though slightly thicker in vi–xx.

Alimentary canal. Pharynx in ii–iv covered in slender transeptal muscle bands, whitish in color, in numerous distinct layers over dorsal and lateral surfaces of the pharynx, extending posteriorly, anchored in body wall. Two gizzards in v–vi without distinct demarcation also with numerous transeptal muscle bands extending posteriorly for one or two segments. Esophagus vii–xvii, generally uniform in diameter (about 0.7 mm) from xiii–xv. Calciferous glands or lamellae absent. Intestinal origin xviii fully expanded (1.8 mm diameter) at junction with esophagus at septum xvii/xviii with few exceptions where intestine tapers to full diameter in xviii. Simple lamelliform typhlosole begins in or near xxi and extends over half of intestinal length, protrudes about 0.5 mm into lumen or 1/4 to 1/3 of the inside lumen diameter. Gut lining smooth with few ridges.

Nephridia . Holoic, in iii to terminal segments near periproct. Tubules 2–3 loops, overall length 3–4 mm, diameter uniform less than 0.1 mm. Exoic duct exits coelom anterior to d. Avesiculate.

Vascular system . Dorsal vessel single throughout. Ventral vessel most easily observed in xv–xvii dorsad and in contact with the ventral nerve cord. Paired latero-esophageal vessels (hearts) x, xi, and xii often engorged with blood. Extra-esophageal vessels vii–ix, less diameter than hearts and occupy same position in each segment as the hearts.

Nervous system . Dorsal bi-lobed cerebral ganglion on dorsal surface of pharynx in iii united with ventral nerve cord by circumpharyngeal connectives that pass over the lateral surface of the pharynx. Ventral nerve cord 0.2 mm diameter easily observed in xv–xvii, sandwiched between the ventral blood vessel and body wall.

Male sexual system . Testes holandric, inconspicuous, lack iridescence, in x and xi. Male funnels, iridescent and conspicuous (ca. 0.8 mm dia.), attached to anterior surfaces of septa 10/11 and 11/12. Racemose seminal vesicles in ix half the size of those in xii. Prostates paired in xix and xxi. Sharp transition in diameter from duct to gland. Prostatic duct straight and short (0.2 mm long) and narrow (<0.1 mm dia.). Gland (ca. 0.4 mm dia.) with smooth margin and sharp folds with asymmetrical distribution of R/L anterior/posterior prostates that span three or more pre-segments and five or more post-segments. Penisetal bundles and transverse muscle bands absent in xix and xxi.

Female sexual system . Ovaries in xiii, conspicuous cluster, no distinct strings, attached to ventrad posterior surface of septum 12/13. Ovarian funnels conspicuous, attached to ventrad anterior surface of septum 13/14, irregular wavy rim ca. 0.3 mm diameter. Oviducts pass through 13/14 septum, short duct in xiv ca. 0.2 mm diameter, penetrates body wall adjacent to ventral nerve cord, mesiad to a.

Spermathecae. Quadrithecal, in viii and ix. Duct emerges near a, length about 1─ 2 mm long by <1 mm diameter. Acryptate. Diverticulum (length twice as long as width) sessile or short stalk (<0.1 mm) attached near base of ampulla; oblong quadruple seminal chamber; iridescence on most specimens. Ampulla ovoid, relatively large compared to overall size of clitellate specimens, 2.4 mm long by 1.8 mm wide ( Fig. 2 ).

Remarks

Gut ingesta varies according to soils at diverse sites. Most specimens with an abundance of fine sand, with a few sand grains larger than diameter of esophagus (range <0.01–1.0 mm dia.). Light brown fine-grained organic material suspended in coagulated mucus. Large (ca. 0.5 mm dia.) opaque white spheres with a globular surface, perhaps calcium aggregates, randomly distributed in the ingesta, similar in distribution and scarcity as the large sand grains.

Ingesta of the White Oak Spring (WOS) specimens limited to relatively low amount of very fine sand and an abundance of dark brown (Munsell 7.5 YR 3/3) hemic organic matter. The spring is in a deep narrow ravine with a nearly closed canopy of white oak ( Quercus sp. ), bigtooth maple ( Acer grandidentatum ), Texas madrone ( Arbutus xalapensis ), very little understory vegetation, and a deep layer of leaf litter over deep silt loam soil. Even here, though, earthworms were in soils well above the spring pool. The specimens from the north end of WOS appeared post reproductive as evidenced by slight rings of brown pigment in the preclitellar intersegmental furrows, a lack of iridescence on diverticula and male funnels, less prominent spermathecal pores than most other adult specimens collected at the other sites, and spermathecae that appeared collapsed.

Five D. eiseni specimens, along with Aporrectodea rosea , were collected in a black loam hydric soil of the Black River in Eddy County; D. farrishi was not collected at this site. Elsewhere in the USA, it is our observation that D. eiseni is often found in hydric soils. In the numerous papers referenced above where James collects purported D. verrucosa he also reports D. smithii . Our single collection of D. smithii (along with numerous Ap. rosea ) is from one site on a ledge 3 m above a small stream. D. texensis , with a male groove that spans xx—xxii, was collected at three sites associated with hydric soils and never collected with D. farrishi . The only earthworm species collected at the White Oak Spring site was D. farrishi , the site from which the holotype was selected.

Because of the unique region from which D. farrishi was collected, we propose as a common name the Chihuahuan Desert earthworm.

Figures

FIGURE 2. Diplocardia verrucosa: (A) ventral view, spermathecae from (B) viii, and (C) ix; Diplocardia farrishi sp. nov.: (D) ventral view, spermathecae from (E) viii, and (F) ix. SP, spermathecae pores; F, female pores; P, prostatic pores; and M, male pores.