Spinodiosaccus primus, Gómez & Corgosinho & Rivera-Sánchez, 2021

Gómez, Samuel, Corgosinho, Paulo Henrique Costa & Rivera-Sánchez, Karen I., 2021, Proposal of new genera and species of the subfamily Diosaccinae (Copepoda: Harpacticoida: Miraciidae), European Journal of Taxonomy 759 (1), pp. 1-62 : 27-38

Spinodiosaccus primus gen. et sp. nov.

urn:lsid:zoobank.org:act:4B5EB240-AC9A-4F68-A79F-BADEF42F6880

Figs 11–18

Etymology

The specific epithet comes from the Latin ‘prīmus’, ‘first’, and refers to the first – and type – species described for Spinodiosaccus gen. nov. It is in the nominative singular, gender masculine.

Material examined

Holotype MEXICO • ♀ (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 5 (see also Gómez 2020a: 43, fig. 1); 23.2056° N, 106.3715° W; 0.6 m depth; 18 Jan. 2019; S Gómez leg.; organic carbon content 0.99%, organic matter content 1.71%, sand 78.61%, clay 6.72%, silt 14.67%); ICML- EMUCOP-180119-57.

Allotype MEXICO • ♂ (preserved in alcohol); same collection data as for holotype; ICML-EMUCOP-180119-58 .

Paratypes MEXICO • 7 ♀♀, 5 ♂♂ (preserved in alcohol); same collection data as for holotype; ICML- EMUCOP-180119-59 • 1 ♀ (preserved in alcohol); same collection data as for holotype; ICML- EMUCOP-180119-60 • 2 ♀♀, 3 ♂♂ (preserved in alcohol); same collection data as for holotype; ICML- EMUCOP-180119-61 • 1 ♀ (dissected); same collection data as for holotype; ICML-EMUCOP-180119- 64 • 1 ♀ (dissected); same collection data as for holotype; ICML-EMUCOP-180119-65 • 1 ♀ (dissected); same collection data as for holotype; ICML-EMUCOP-180119-66 • 1 ♂ (dissected); same collection data as for holotype; ICML-EMUCOP-180119-67 • 1 ♂ (dissected); same collection data as for holotype; ICML-EMUCOP-180119-68 • 1 ♂ (dissected); same collection data as for holotype; ICML- EMUCOP-180119-69 • 1 ♀ (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 6 (see also Gómez 2020a: 43, fig. 1); 23.2123° N, 106.3780° W; 1.4 m depth; 18 Jan. 2019; S. Gómez leg.; organic carbon content 1.65%, organic matter content 2.84%, sand 61.44%, clay 14.57%, silt 23.99%; ICML-EMUCOP-180119-63 .

Other material

MEXICO • 3 ♀♀, 6 ♂♂, 4 CV (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 2 (see also Gómez 2020a: 43, fig. 1); 23.1587° N, 106.3326° W; 1.8 m depth; 18 Jan. 2019; S. Gómez leg.; organic carbon content 3.99%, organic matter content 6.86%, sand 80.42%, clay 8.29%, silt 11.28%; ICML-EMUCOP-180119-70 • 1 ♀, 1 ♂ (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 4 (see also Gómez 2020a: 43, fig. 1); 23.1840° N, 106.3579° W; 0.7 m depth; 18 Jan. 2019; S. Gómez leg.; organic carbon content 1.13%, organic matter content 1.94%, sand 82.44%, clay 8.27%, silt 9.29%; ICML-EMUCOP-180119-71 • 1 ♀ (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-72 • 2 CV (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-73 • 1 CV (preserved in alcohol); same collection data as for holotype; ICML-EMUCOP-180119-62 • 1 CV, 1 CIII (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 6 (see also Gómez 2020a: 43, fig. 1); 23.2123° N, 106.3780° W; 1.4 m depth; 18 Jan. 2019; S. Gómez leg.; organic carbon content 1.65%, organic matter content 2.84%, sand 61.44%, clay 14.57%, silt 23.99%; ICML-EMUCOP-180119-74 • 2 ♂♂ (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-75 • 2 ♀♀, 2 ♂♂ (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-76 • 1 ♀, 1 ♂ (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 9 (see also Gómez 2020a: 43, fig. 1); 23.1904° N, 106.4121° W; 5.4 m depth; 18 Jan. 2019; S. Gómez leg.; organic carbon content 1.41%, organic matter content 2.43%, sand 64.81%, clay 8.09%, silt 27.11%; ICML-EMUCOP-180119-77 • 4 ♂♂, 1 CV (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-78 • 3 ♂♂, 1 CV (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-79 • 1 ♂ (preserved in alcohol); Sinaloa State, Mazatlán, Urías coastal system, stn 10 (see also Gómez 2020a: 43, fig. 1); 23.1815° N, 106.4214° W; 6.0 m depth; 18 Jan. 2019; S. Gómez leg.; organic carbon content 1.2%, organic matter content 2.07%,m sand 69.12%, clay 7.91%, silt 22.97%; ICML-EMUCOP-180119-80 • 1 ♂ (preserved in alcohol); same collection data as for preceding; ICML-EMUCOP-180119-81 .

Description

Female

GENERAL. Total body length measured from tip of rostrum to posterior margin of caudal rami ranging from 510 to 695 µm (mean 605.4 µm; n = 13; total body length of holotype 695 µm); habitus fusiform, widest at posterior end of cephalothorax in dorsal view, tapering posteriad ( Fig. 11A ).

PROSOME ( Fig. 11A, C ). Consisting of cephalothorax, with fused first pedigerous somite, and second to fourth free pedigerous somites; prosomites without expansions nor spinular ornamentation; posterior hyaline frill of cephalothorax, second and third pedigerous somites broad, of P4-bearing somite visibly narrower, with posterior margins plain; posterior frill of second and third pedigerous somites with transverse row of minute spinules.

UROSOME ( Figs 11A–D , 12A ). Consisting of fifth pedigerous somite (first urosomite), genital doublesomite (genital – second urosomite – and third urosomites fused), two free urosomites, anal somite and caudal rami; urosomites without expansions. First urosomite narrower than preceding somites in dorsal view ( Fig. 11A ), without spinular ornamentation, with posterior sensilla as depicted, with one lateral pore on each side ( Fig. 11C ), posterior frill as in preceding somite dorsally and laterally ( Fig. 11A, C ). Genital double-somite ( Figs 11A, C , 12A ) rectangular, slightly longer than wide, with sensilla as shown, without spinular ornamentation; original division between anterior and posterior halves (second – genital – urosomite and third urosomite, respectively) marked by inner cuticular rib dorsally and laterally ( Fig. 11A, C ), completely fused ventrally ( Fig. 12A ); posterior half of genital double-somite with two dorsal pores and one lateroventral pore on each side, with posterior hyaline frill finely serrated and striated; P6 at anterior third of genital somite (anterior half of genital double-somite) and with genital field as shown ( Fig. 12A ). Fourth urosomite largely as in posterior half of genital double-somite, but with additional medial pore ventrally and posterior ventrolateral transverse spinular row on frill ( Figs 11A, C , 12A ). Fifth urosomite without sensilla or spinules, with two dorsal and two ventral pores, posterior hyaline frill as in preceding somites ( Figs 1A, C , 12A ). Anal somite wider than long in dorsal view ( Fig. 11A–B ), without anal operculum, cleft medially dorsally ( Fig. 11A–B ) and ventrally ( Fig. 12A ), with two posterior sensilla dorsally, two dorsolateral pores ( Fig. 11A–C ) and two ventral pores ( Fig. 12A ), dorsally without spinules, with one ventrolateral and one short ventral spinular row on each side close to joint with caudal rami as shown ( Fig. 12A ). Caudal rami short, twice as wide as long in dorsal view ( Fig. 11A–B ), unornamented, with slender tube pore ventrally; with seven setae ( Figs 1B, D , 2A ) as follows: setae I and II situated almost medially on outer margin, the former very small and ventral to the latter; seta III displaced ventrally close to outer margin; setae IV and V normal, with fracture plane, the former shorter; seta VI arising at inner distal corner; dorsal seta VII issuing subdistally, close to inner margin, triarticulated.

ROSTRUM ( Fig. 13A ). Not fused to cephalothorax, elongate, triangular, with blunt tip, with one sensillum arising at distal third on each side, without pore, reaching distal margin of second antennulary segment.

ANTENNULE ( Fig. 13B–C ). Eight-segmented; all segments smooth, except for one proximal and one subdistal short spinular row on first segment; all setae smooth; with two and four biarticulated setae on penultimate and last segments, respectively. Armature formula: 1(1); 2(10); 3(6); 4(3 +(1 +ae)); 5(2); 6(4); 7(4); 8(5+ acro). Acrothek consisting of two setae and one aesthetasc fused basally.

ANTENNA ( Fig. 13D ). With small coxa ornamented with outer spinules. Allobasis with remains of former division between basis and first endopodal segment, as long as free endopodal segment, with outer spinules proximally, with one abexopodal seta. Exopod three-segmented; first and third ones subequal in length, second segment smallest; first and second segments unornamented, with one seta each; third segment unornamented, with four elements – one proximal bipinnate, one small subdistal and two distal spine-like elements. Free endopodal segment with proximal and subdistal inner strong spinules, and with row of outer small spinules as shown; armed with two lateral inner spines and two slender setae, the latter set close to each other, one inner apical spine, three single geniculate setae, one slender seta, and one strongly spinulose geniculate outer seta fused basally to slender pinnate element.

MANDIBLE ( Fig. 14A ). With well-developed gnathobasis bearing strong multi- and bicuspidate teeth as shown, with two long spinules and one pinnate seta. Basis massive, with strong spinules, with three inner setae. Exopod two-segmented; first segment longer than second, the former with one lateral and one distal seta, the latter with three apical elements. Endopod one-segmented, visibly larger than exopod; with two lateral and six distal setae, of which three fused basally.

MAXILLULE ( Fig. 14B ). With arthrite ornamented with some slender spinules and armed with two surface setae (the latter indicated with an asterisk on figure), seven distal spines as shown, one spinulose element and one recurved, stiff pinnate seta. Coxal endite with two setae. Basis with spinular rows as depicted and armed with three lateral, one subdistal and three distal elements, one of which visibly stronger. Rami one-segmented, exopod unornamented and with two setae, endopod with longitudinal spinular row and with four elements – one inner subdistal, two distal and two outer subdistal setae.

MAXILLA ( Fig. 14C ). With large syncoxa ornamented with small outer spinules; with three endites; proximal endite smallest, with two setae; middle endite longer than proximal endite, with two setae; distal endite longest, with three setae. Basis drawn out into strong claw, additionally with pinnate spine, and two slender setae – one anterior, one posterior. Endopod one-segmented, with one proximal, one medial, one subdistal and four apical setae.

MAXILLIPED ( Fig. 14D ). Subchelate. Praecoxa small. Coxa elongate, with proximal, medial and subdistal spinules as shown; with two inner small setae issuing at middle of segment and two long apical setae. Basis longer than coxa, elongate, with medial row of small spinules and with longitudinal row of minute outer spinules, with one medial inner and one subdistal inner seta. Endopod one-segmented, elongate, with apical claw and three setae of different lengths.

P1 ( Fig. 15A ). With unornamented intercoxal sclerite. Coxa massive, with several spinular rows as shown. Basis with inner and outer spinulose spines; with strong spinules at top of crescentic medial extension, and with smaller spinules at base of inner spine. Exopod three-segmented, arising at a lower level than that of endopod and reaching tip of ENP2; ENP: EXP length ratio 1.2; exopodal segments with strong outer spinules as shown; second segment shortest, third segment longest; first and second segments without inner armature, outer spine of first segment longer than that of second segment; third segment with five elements of which outer proximal and medial spines shorter than those of preceding segments. Endopod three-segmented, arising from pedestal; ENP1 about 2.8 times as long as wide, 1.4 times as long as second and third segments combined, with outer longitudinal row of strong spinules, with one inner stiff, long, strongly pectinate seta; second and third segments with strong outer spinules as shown, the former shorter, slightly longer than wide, with one inner seta; third segment elongate, 1.5 times as long as preceding segment, with one inner distal slender seta, one apical long element and one outer distal spine.

P2 ( Fig. 15B ). With narrow intercoxal sclerite unornamented, with acute distal projection on each side. Coxa with three anterior rows of spinules. Basis with small inner acute outgrowth, with long slender inner spinules, with minute spinules at base of endopod, and with strong spinules between rami and at base of outer spine. Rami three-segmented, endopod longer than exopod. Exopod three-segmented, arising at a lower level than that of the endopod, reaching slightly above the middle of ENP3; exopodal segments with strong outer spinules as shown; EXP1 and EXP2 with outer distal acute projection, of EXP1 shorter, inner distal frill of first segment coarse, of second segment small, first segment without, second segment with inner seta; EXP3 with subdistal outer pore and seven elements – three outer spines, two apical elements and two inner setae of which distalmost one visibly shorter. Endopod three-segmented, arising from pedestal; endopodal segments with strong outer spinules as shown; ENP1 shortest, slightly longer than wide, with posterior small spinules proximally, with small inner distal spinules and with outer short acute projection, with one short inner seta; ENP2 elongate, twice as long as wide and 0.6 times as long as ENP3, with small inner distal spinules, with long outer distal acute projection, with two inner setae of which proximal shorter; ENP3 longest, elongate, six times as long as wide, with four elements (one inner and two apical setae, and one outer spine), with acute projection between outer spine and inner apical seta.

P3 ( Fig. 16A ). With triangular praecoxa ornamented with transverse row of minute spinules. Intercoxal sclerite and coxa as in P2. Basis largely as in P2, but with smaller inner distal outgrowth and setiform outer element. Rami three-segmented, endopod slightly longer than exopod. Exopod largely as in P2. Endopod largely as in P2 except for lack of posterior spinules and with outer subdistal pore on ENP1, for inner seta of P3 ENP1 comparatively longer, for one long seta only on P3 ENP2, and for two inner setae on P3 ENP3.

P4 ( Fig. 16B ). With intercoxal sclerite, praecoxa, and coxa as in P3. Basis as in P3 except for lack of inner distal outgrowth. Exopod longer than endopod; EXP: ENP length ratio 1.3; largely as in P3 except for three inner setae on P4 EXP3 of which medial one visibly thicker and strongly pectinate. Endopod reaching slightly beyond middle of EXP3; largely as in P3 except for one inner seta only on P4 ENP3.

Armature formula of P1–P4 as follows: P5 ( Fig. 12C ). With outer seta of baseoendopod arising from setophore. Endopodal lobe triangular, reaching distal third of exopod; with small spinules along outer margin; with five elements – one outer and one inner apical and one inner subdistal long setae, and two inner spiniform elements. Exopod elongate, 2.2 times as long as wide; with spinules at base of innermost seta and on outer margin proximally; with six elements – three outer slender setae, two apical elements of which outermost one shorter and one inner seta.

P6 ( Fig. 12A ). With three setae – one short bipinnate element, and one medial and one inner slender seta.

Male

GENERAL. Total body length measured from tip of rostrum to posterior margin of caudal rami ranging from 380 to 510 µm (mean 455 µm; n = 8; total body length of allotype 510 µm).

PROSOME ( Fig. 17A ). As in female.

UROSOME ( Fig. 17A–B ). As in female except for second – P6-bearing somite – and third urosomites separated, for medial row of eight ventral spinules on third urosomite, and for lack of spinules on hyaline frill of fourth urosomite.

SEXUAL DIMORPHISM. Expressed in ventral somatic ornamentation (see above), antennule, and basis of P1, P2 ENP, P5 and P6.

ANTENNULE ( Fig. 18A–B ). 11-segmented, haplocer. All segments smooth, except for proximal and subdistal spinular rows on first segment. All setae smooth except for two and four biarticulated setae on tenth and eleventh segments, respectively. Armature formula: 1(1); 2(11); 3(6); 4(1); 5(5+(1+ ae)); 6(2); 7(2 +2 spines); 8(0); 9(1); 10(4); 11(5+ acro). Acrothek consisting of two setae and one aesthetasc fused basally.

ANTENNA, MANDIBLE, MAXILLULE, MAXILLA AND MAXILLIPED (not shown). As in female.

P1. As in female except for basis without slender inner long spinules, without spinules at base of inner spine and with inner modified accessory spine ( Fig. 18C ).

P2 EXP (not shown). As in female. Endopod ( Fig. 18D ) sexually dimorphic, two-segmented; ENP1 as long as ENP2 (excluding distal cylindrical extension of ENP2), with longitudinal row of outer spinules, with outer distal acute outgrowth, with one inner short seta; proximal part of ENP2 rectangular, distal extension cylindrical, 2.4 times as long as wide excluding distal cylindrical extension, with longitudinal row of outer spinules, with two inner setae arising from pedestal of which proximal (seta I on Fig. 18D ) visibly shorter, subdistally with one strong inner and almost straight element (element III on Fig. 18D ), with one lateral and one apical seta (setae IV and V on Fig. 18D ) arising from distal elongate cylindrical extension fused to segment basally and with strong outer subdistal element strongly tapering distally (element VI on Fig. 18D ).

P3 AND P4 (not shown). As in female.

P5 ( Fig. 18E ). With outer seta of baseoendopod arising from setophore. Endopodal lobe reaching middle of exopod, with outer spinules as shown, with two distal modified setae as shown of which outermost one shorter. Exopod triangular, 1.6 times as long as wide, with inner subdistal pore, with six setae – one proximal bipinnate seta, one medial and one subdistal short strong spines of which medial one shorter, one distal seta arising from setophore and two inner setae of which proximal one shorter.

P6 ( Fig. 17B ). Asymmetrical, only one leg functional, each leg with three setae of which innermost one bipinnate, medial longest and bare, outermost shortest and bare.

Variability

Both caudal setae I spiniform in one female. One male possesses only one outer spine on P5 EXP.

Figures

Fig. 11. Spinodiosaccus primus gen. et sp. nov., holotype, ♀ (ICML-EMUCOP-180119-57). A. Habitus, dorsal view. B. Anal somite and caudal rami, dorsal view. C. Habitus, lateral view. D. Left caudal ramus, lateral view.

Fig. 12. Spinodiosaccus primusgen. et sp. nov., paratype, ♀ (ICML-EMUCOP-180119-64). A. Urosome, ventral view (P5-bearing somite omitted). B. Caudal setae IV and V, ventral view. C. P5, anterior view.

Fig. 13. Spinodiosaccus primus gen. et sp. nov., paratype, ♀ (ICML-EMUCOP-180119-64). A. Rostrum, dorsal view. B. Antennule (armature omitted for simplicity). C. Antennule showing armature. D. Antenna.

Fig. 14. Spinodiosaccus primus gen. et sp. nov., paratype, ♀ (ICML-EMUCOP-180119-64). A. Mandible. B. Maxillule (asterisk indicates two surface setae). C. Maxilla. D. Maxilliped.

Fig. 15. Spinodiosaccus primus gen. et sp. nov., paratype, ♀ (ICML-EMUCOP-180119-65). A. P1, anterior view. B. P2, anterior view.

Fig. 16. Spinodiosaccus primus gen. et sp. nov., paratype, ♀ (ICML-EMUCOP-180119-65). A. P3, anterior view. B. P4, anterior view.

Fig. 17. Spinodiosaccus primus gen. et sp. nov. A. Allotype, ♂ (ICML-EMUCOP-180119-58); habitus, lateral view. B. Paratype, ♂ (ICML-EMUCOP-180119-67); urosome, ventral view (P5-bearing somite omitted).

Fig. 18. Spinodiosaccus primus gen. et sp. nov. A–B, E. Paratype, ♂ (ICML-EMUCOP-180119-68). C–D. Paratype, ♂ (ICML-EMUCOP-180119-69). A. Antennule (armature omitted for simplicity). B. Antennule showing armature. C. Basis of P1, anterior view. D. P2 ENP. E. P5, anterior view.

Fig. 1. Typhlamphiascus medici sp. nov., holotype, ♀ (ICML-EMUCOP-180119-40). A. Habitus, dorsal view. B. Anal somite and caudal rami, dorsal view. C. Habitus, lateral view. D. Anal somite and left caudal ramus, lateral view.

Fig. 2. Typhlamphiascus medici sp. nov., paratype, ♀ (ICML-EMUCOP-180119-41). A. Urosome, ventral view (P5-bearing somite omitted). B. P5, anterior view.

Armature formula of P1–P4 as follows: P5 ( Fig. 12C ). With outer seta of baseoendopod arising from setophore. Endopodal lobe triangular, reaching distal third of exopod; with small spinules along outer margin; with five elements – one outer and one inner apical and one inner subdistal long setae, and two inner spiniform elements. Exopod elongate, 2.2 times as long as wide; with spinules at base of innermost seta and on outer margin proximally; with six elements – three outer slender setae, two apical elements of which outermost one shorter and one inner seta.