Lavellodrilus sheylae, Fragoso & Rojas, 2018

Fragoso, Carlos & Rojas, Patricia, 2018, New Diplotrema and Lavellodrilus earthworm species from southern Mexico (Annelida, Crassiclitellata, Acanthodrilidae), Zootaxa 4496 (1), pp. 414-430 : 421-428

Lavellodrilus sheylae sp. nov.

( FigurES 3 , 4 , 5 )

Localities and material. MExico, TabaSco: 1) RanchEria of San JoSE PuyacatEngo, municipality of TEapa, km 7 of road TEapa-VicEntE GuErrEro, foothillS of CErro Madrigal, 50 yr traditional Cocoa plantation without intEnSivE uSE of agrochEmicalS, cloSE to rivEr PuyacatEngo at 0–10 cm dEpth, 17°31'36.91''N, 92°55'44.23''W, 80 m aSl, four clitEllatE adultS 06/30/2002, ShEyla UribE; 2) RanchEria of San JoSE PuyacatEngo, municipality of TEapa, km 7 of road TEapa-VicEntE GuErrEro, high landS of CErro Madrigal, diSturbEd tropical forESt at 0–10 cm dEpth, 17°31'33.21''N, and 92°55'30.47''W, 240 m aSl, onE clitEllatE adult 11/06/2002, ShEyla UribE; 3) Comalcalco, Municipality of Comalcalco, 1.2 km South of town, on thE road to JoSE Maria Pino SuarEz, Cocoa plantation with intEnSivE uSE of agrochEmicalS for morE than 10 yEarS at 0–10 cm dEpth, 18°13'35.8''N, 93°13' 33.1''W, 13 m aSl, thrEE clitEllatE adultS, 01/30/2004, ShEyla UribE. ( Fig. 6 ).

Holotype. EntirE clitEllatE adult with gEnital markS (GM) and pEnial SEtaE (PS) collEctEd in locality 1, 06/30/ 2002: IEOL 4831.

Paratypes. ThrEE EntirE clitEllatE adultS from locality 1: 06/30/2002: IEOL 4830, IEOL 4832, IEOL 4837; onE EntirE clitEllatE adult from locality 2: 11/06/2002: IEOL 4832; thrEE clitEllatE adultS from locality 3 01/30/2004: onE cut in two piEcES, IEOL 4833, and two almoSt cut at clitEllum lEvEl, IEOL 4834 and IEOL 4835.

Description. External. LEngth 17.6–30 mm (avEragE 23.5, n=8), holotypE 25 mm. Width, middlE body: 0.88– 1.1 mm (avEragE= 1, n= 8); holotypE 1.1 mm. NumbEr of SEgmEntS 79–87 (avEragE= 83, n= 8); holotypE 87 SEgmEntS. ThE majority of SEgmEntS widEr than long ( Fig 3A,D ); aftEr clitEllum SomE SEgmEntS almoSt aS long aS widE. PigmEnt abSEnt. ProStomium prolobic, invaginatEd in thE majority of individualS. SEcondary furrowS barEly viSiblE; if prESEnt onE poStSEtal aftEr clitEllum. SEtaE Eight pEr SEgmEnt, viSiblE from 2 ( Fig. 3A,D ); cloSEly pairEd throughout. SEtal formula (avEragES, n=3) (aa:ab:bc:cd:dd) at 10: 5.2:1:6.2:0.8:15 and 1.2 dd =1/2 C; at 30: 5.9:1:6:1.2:19.1 and 1.4 dd =1/2 C; tEn SEgmEntS bEforE anuS: 6.4:1:6:1.2:17 and 1.3 dd =1/2 C. PEnial SEtaE in 17 and 19 ( Fig. 5 ); vEry difficult to Extract, and with a dimorphiSm charactErizEd by diffErEnt SizE and ornamEntation. ThE largEr a SEta (lEngth: 391, 415, 416, 420 µm; width: 11, 17, 17, 29 µm) almoSt Straight or Slightly brackEt-ShapEd ( Fig. 5A ) with diStal half undulatEd ( Fig. 5B ) and with a hook- or claw-ShapEd apEx ( Fig 5C,E ); ornamEntation charactErizEd by irrEgular and ScarcE thornS or notchES juSt bEforE thE apEx ( Fig. 5C,D ); in SomE individualS, thE SEta apparEntly within a covEr, but apEx frEE ( Fig. 5C ). ThE ShortEr b SEta (lEngth: 315 µm; width: 12.3 µm) Slightly curvEd ( Fig. 5F ) and with an acutE apEx curvEd 90° or morE in thE SamE dirEction of curvaturE ( Fig. 5H ); no undulationS arE prESEnt and ornamEntation charactErizEd by irrEgular notchES ( Fig 5G ), limitEd to diStal End juSt bEforE apEx ( Fig. 5H ). GEnital SEtaE abSEnt. ClitEllum dark or light orangE, SaddlE-ShapEd, in 13–17, vEntrally rEaching BC (cloSE to B) or A ( Fig. 3A,D ). DorSal porES prESEnt all along thE body, firSt porE in 10/11 (7 individualS) or 11/12 (onE individual). SpErmathEcal porES mESial in 7/8 and 8/9, vEry Small, only SEEn in two individualS ( Fig. 3D ). FEmalE porES in 14, prESEtal, mEdian to a; in SomE individualS within a bilobular or ovoidal papilla ( Fig. 3C ). Two pairS of mESial proStatic porES in 17 and 19, ovEr Elliptical prominEncES tranSvErSally oriEntEd; from thE prominEncES, SEminal groovES curvE 90° to continuE ovEr AB in SEgmEnt 18 ( Fig. 3A,B,D ) Surrounding gEnital markS. MalE porES not SEEn, probably within SEminal groovES and opEning SomEwhErE in 18. GEnital markS aS pairEd papilla locatEd in 16 and 18, Each onE ExtEnding from midvEntral linE to B and occupying all or ¾ of thE rESpEctivE SEgmEnt. ThoSE of 16 ovoidal and longitudinally oriEntEd; thoSE of 18 largEr and almoSt circular ( Fig. 3A,B,D ).

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Internal. SEptum 5/6 thin, Slightly muScular, in SomE individualS almoSt mEmbranouS; SEpta 6/7–11/12 muScular; SEptum 12/13 thin but Still muScular; SEptum 13/14 and backwardS mEmbranouS and thin; SEpta 5/6–10/ 11, and in SomE individualS alSo 11/12, funnEl-ShapEd and Slightly imbricatEd. OnE largE rEctangular gizzard in 5. Gizzard dimEnSionS (lEngth by width): 0.36 by 0.64 mm (holotypE), 0.54 by 0.65 mm (ParatypE IEOL 4836). ESophaguS in 9–12 without intErnal lamEllaE; vaScularization in ESophagEal wallS variablE, in SomE individualS prESEnt in SEgmEntS 8–10 in othErS in 9–12; dilatationS rESEmbling pouchES fairly conStant in SEgmEntS 10 and 11 (obSErvEd in 7 individualS, including holotypE); thEy could corrESpond to ESophagEal glandS, mainly bEcauSE in SomE individualS thEy arE highly vaScularizEd. IntEStinE Starting in 13/14 (6 ind.) ( Fig. 4A ). A laminar dorSal typhloSolE StartS abruptly with maximal SizE in SEgmEnt 15, diminiShing 2–3 SEgmEntS poStEriorly to a normal SizE (not morE than ½ of lumEn) until SEgmEntS 20, 24 (thrEE ind.) or 31, 34 (thrEE ind.), whErE it abruptly dEcrEaSES in SizE to a wEak ribbon-likE StructurE; thiS ribbon gradually diminiShES in SizE, Ending 20 or 39 SEgmEntS bEforE anuS. LatEral typhloSolES abSEnt.

SinglE dorSal vESSEl viSiblE throughout; in 15 and 16 conSpicuouSly EnlargEd, and coincidEnt with largEr dorSal typhloSolE ( Fig. 4A ); in two individualS (IEOL 4832, 4837) doublE in 16 and with latEral vESSElS full of blood in 15/16 and 16/17 ( Fig. 4B ). Supra-ESophagEal vESSEl clEarly viSiblE in SEgmEntS 11 and 12; in 10 SEEn only in onE individual. LatEral hEartS in 9 and 10; latEro-ESophagEal hEartS in 11 and 12. VEntral vESSEl prESEnt. Extra pariEtal latEral-vEntral vESSElS prESEnt, viSiblE EvEn from thE ExtErior; thEy run ovEr BC, Starting in SEgmEntS 14 (1 ind.), 16 (1) ( Fig. 4C ), 17 (1), 18 (3) or 19 (1), bEing Still conSpicuouS and viSiblE in SEgmEntS 25, 27, 28; in two individualS Still viSiblE in SEgmEntS 40, 41. A pair of infra-ESophagEal vESSElS in 10 and 11, viSiblE only in thE holotypE. Holoic without vESiclES. ThE ExonEphric, and apparEntly StomatE holonEphridia arE vEntro-pariEtal from SEgmEnt 7; from thiS SEgmEnt nEphridia gradually movE towardS latEral-pariEtES, bEing complEtEly pariEtal from 13 backwardS ( Fig. 4A ). NEphroStomES and nEphroporES not SEEn. Holandric. IridiScEnt malE funnElS in 10 and 11; tEStES difficult to SEE; rEcordEd only in two individualS, in SEgmEnt 11. MalE gonoduct zigzagging, doublE, Supra-pariEtal, obSErvEd only in two individualS in SEgmEntS 13–16. OnE pair of SEminal vESiclES in 12, Small and partially covEring thE ESophagouS. Two pairS of Small tubular proStatES in 17 and 19, with onE fold, limitEd to itS SEgmEntS or ExtEnding to adjacEnt antErior or poStErior SEgmEnt ( Fig. 4C ); in two individualS Spirally coilEd; glandular part 2–4 timES largEr than muScular rEgion. PEnial SEtaE folliclES fixEd to floor and latEral wallS, limitEd to thEir rESpEctivE SEgmEntS.

PairEd ovariES and fEmalE funnElS in 13. OvariES fan or (mainly) buSh-ShapEd, vEry largE and with conSpicuouS EggS not arrangEd in rowS; fEmalE funnElS fixEd to floor and vEry cloSE to mid-vEntral linE. Only two SpErmathEcaE, onE opEning in 7/8 and thE othEr onE in 8/9. AntErior and poStErior SpErmathEcaE locatEd in SEgmEntS 8 and 9, rESpEctivEly (6 ind.); or locatEd in 7 and 9 (1 ind.); or both locatEd in 8 (1 ind.). Two typES of SpErmathEcaE rEcordEd: in two individualS (paratypES 4830 and 4832) Each SpErmathEca with a SinglE, latEral divErticulum ( Fig. 4C ); holotypE and othEr paratypES with two latEral and oppoSitE divErticula pEr SpErmathEca ( Fig. 4D ). In both typES of SpErmathEcaE, divErticula EmErgE from Ental rEgion of duct; duct aS widE aS ampulla or Slightly narrowEr, oriEntEd along thE SamE axiS. DivErticula with SpErm inSidE in all but paratypE 4832, half or lESS aS half aS widE aS duct or ampulla. MEaSurEd lEngthS of SpErmathEcaE, onE divErticulum typE: antErior 0.34, 0.38 mm, poStErior 0.41, 0.44 mm; two divErticula typE: antErior 0.53 mm, poStErior 0.50, 0.56 mm.

Etymology. ThE namE of thE SpEciES iS dEdicatEd to Dr. ShEyla UribE, in rEcognition of hEr EnthuSiaSm and EffortS to Study thE EarthwormS of TabaSco StatE.

Remarks. L. sheylae sp. nov. iS uniquE in thE gEnuS by thE unpairEd condition of antErior (diScharging in 7/8) and poStErior (diScharging in 8/9) SpErmathEcaE ( TablE 2), a condition not obSErvEd in any of thE holoic acanthodrilinES prESEnt in MExico, Cuba and CEntral AmErican or thE holoic and mEroic diplocardinES from northErn MExico, USA and thE CaribbEan ( FragoSo & RojaS 2016). Although unpairEd SpErmathEcaE arE quitE frEquEnt in SEvEral BEnhamiinaE acanthodrilid gEnEra ( CSuzdi 2010), thiS unpairEd condition of SpErmathEcaE in SuccESSivE SEgmEntS iS not obSErvEd in any of thE world acanthodrilinES rEcEntly rEviSEd by FragoSo and RojaS (2016). Only in thE caSE of thE South African SpEciES Parachilota bavenda Pickford 1937 (with mESial SpErmathEcal porES) thE poStErior pairEd SpErmathEcaE arE SubStitutEd by a SinglE onE, whErEaS thE antErior pair iS conSErvEd ( Pickford 1937). In thE caSE of thE mEroic acanthodrilidS from MExico and CEntral AmErica (gEnuS Ramiellona ) thE loSS of thE pairEd condition of SpErmathEcaE haS bEEn obSErvEd in at lEaSt two SpEciES: Ramiellona mexicana GatES, 1962 ( GatES 1962) and anothEr tiny undEScribEd SpEciES from SouthErn MExico ( FragoSo 1993, aS "GEn. nov. 3 Sp. nov. 16 "). In thE firSt caSE (Similar but invErSE to thE pattErn obSErvEd in P. bavenda ), thErE iS onE antErior SpErmathEca with two divErticula and thErE arE two poStErior SpErmathEcaE, Each onE with onE divErticulum; in thE SEcond caSE thErE iS onE antErior SpErmathEca and onE poStErior, Each onE with two divErticula. It SEEmS that in SouthErn MExico thE pattErn of unpairEd SpErmathEcaE opEning to thE ExtErior through mESial porES haS bEEn dEvElopEd indEpEndEntly in SEvEral diffErEnt linEagES. WE will go dEEpEr into thiS aSpEct latEr on.

FurthEr diStinguiShing fEaturES arE a dorSal thyploSolE which StartS with maximal SizE (in thE othEr Lavellodrilus SpEciES it StartS Small, gradually incrEaSing itS SizE), thE highly dEvElopEd dorSal vESSEl in SEgmEntS 15 and 16 (EvEn doublE in SomE individualS) in coincidEncE with a biggEr typhloSolE and a pair of SEminal vESiclES in 12 ( TablE 2). By thE poSition of thE firSt dorSal porE, thE Small body SizE and thE pairEd naturE of gEnital markS, thE nEw SpEciES would bE morE rElatEd to Lavellodrilus parvus FragoSo, 1988 .

Variation in thE numbEr of divErticula (onE or two) for a SinglE SpEciES iS nEw for MExican acanthodrilinES, holoic or mEroic. In othEr rEgionS, howEvEr, SomE variation rElatEd to thE numbEr of SpErmathEcaE haS bEEn obSErvEd. For ExamplE in P. bavenda ( Pickford 1937) , two or thrEE SpErmathEcaE wErE rEcordEd in individualS bElonging to thE SamE or diffErEnt population; intErEStingly, whEn only onE (antErior or poStErior) SpErmathEca waS prESEnt, it waS alwayS on onE SidE and nEvEr midvEntral. WE arE currEntly looking for morE matErial of thiS SpEciES in ordEr to undErtakE COI analySiS of thE two morphotypES. ThE rESulting gEnEtic diStancES (gd) will pErmit to diScriminatE bEtwEEn a SpErmathEcal polymorphiSm (gd<15%) or two diffErEnt SpEciES (gd>15%).

Figures

FIGURE 3. Lavellodrilus sheylae sp. nov. External. A. Ventral view of anterior region of an individual with single diverticulum spermathecae (IEOL 4832; scale 1 mm). B. Latero-ventral view of segments 16–20 of an individual with two diverticula spermathecae (Holotype IEOL 4831) showing genital papillae (Gp) and prostatic pores (Pp) (scale 500 µm) C. Ventral view of segments 14 and 15 showing the papilla (P) that contains female pores (Fp) (Holotype IEOL 4831; scale 500 µm). D. Ventral view of anterior region of an individual with two diverticula spermathecae (IEOL 4836; scale 1 mm).

FIGURE 4. Lavellodrilus sheylae sp. nov. Internal. A. Dorsal view of segments 11–18 (Holotype IEOL 4831; scale 1 mm). B. Dorsal view of segments 15–17 from an individual with two diverticula spermathecae (Paratype IEOL 4837; scale 0.76 mm), showing double dorsal vessel in segment 16 where intestine was cut down to look for typhlosole. C. Parietes of segments 16– 19, showing parietal lateral-ventral vessels and prostates of 17 (P17) and 19 (P19) (Paratype IEOL 4837; scale 0.86 mm). D. Dorso-lateral view of single diverticulum spermatheca of segment 8 (Paratype IEOL 4830; scale 200 µm). E. Dorsal view of two diverticula spermatheca of segment 8 (Paratype IEOL 4833; scale 200 µm). A= ampulla, Di= diverticulum, Du= duct, Dv= dorsal vessel, E=esophagus, H= holonephridium, I= intestine, Lv= parietal lateral ventral vessels.

FIGURE 5. Lavellodrilus sheylae sp. nov. SEM photographs. Large right penial setae a of segment 19 from Paratype IEOL 4830: A. Complete setae (scale 100 µm), B. Undulate region (scale 25 µm), C. Distal region and apex (scale 10 µm); from Paratype IEOL 4833: D. Ornamentation from distal region (scale 10 µm), E. Apex (scale 5 µm). Smaller right penial setae b of segment 19 (Paratype IEOL 4833): F. Complete setae (scale 100 µm), G. Distal ornamentation (scale 5 µm), H. Distal region and apex (scale 5 µm).

FIGURE 6. Geographic distribution of Diplotrema chajulensis sp. nov. and Lavellodrilus sheylae sp. nov.