Tarengoticeps yokotaanensis, Gómez & Morales-Serna, 2015

Gómez, Samuel & Morales-Serna, Francisco Neptali, 2015, On a small collection of Tetragonicipitidae Lang, 1944 (Copepoda: Harpacticoida) from Mexico: new records and new species, Journal of Natural History 49 (45), pp. 2827-2868 : 2851-2859

publication ID	https://doi.org/ 10.1080/00222933.2015.1038329
DOI	https://doi.org/10.5281/zenodo.4330190
persistent identifier	https://treatment.plazi.org/id/D112879B-0624-EE33-D890-FC825737F065
treatment provided by	Carolina
scientific name	Tarengoticeps yokotaanensis
status	sp. nov.

Treatment

Tarengoticeps yokotaanensis sp. nov.

( Figures 16A–D View Figure 16 , 17A–J View Figure 17 , 18A, B View Figure 18 , 19A, B View Figure 19 , 20 View Figure 20 )

Tetragoniceps Brady, 1880 in Gómez and Morales-Serna (2014 , Appendix 2: 121)

Type locality

Off Tabasco State (not Campeche State as in Gómez and Morales-Serna 2014, Appendix 2: 121); 18.6169° N, 93.5° W; 36 m depth GoogleMaps .

Type material

Adult female holotype, dissected (EMUCOP-10–00).

Etymology

The generic name, Tarengoticeps , is an anagram of Tetragoniceps . The specific name yokotaanensis makes reference to the ancient word ‘yoko t’ aan’ which means ‘those of the true language’ and was the name the Chontal people of Tabasco State used to refer to themselves.

Description

Female. Habitus (not shown) fusiform; tapering from posterior margin of cephalothorax to anal somite. Second and third urosomites fused forming genital doublesomite, with remains of former division ventrally, completely fused dorsally. Rostrum ( Figure 16B View Figure 16 ) minute; not fused to cephalothorax.

Antennule ( Figure 16A, B View Figure 16 ). Eight-segmented; first segment elongate, about 2.8 times as long as broad ( Figure 16B View Figure 16 ); second segment slightly longer than broad, without process; armature formula as follows: 1(1); 2(7); 3(8); 4(3+(1+ae)); 5(2); 6(3); 7(4); 8(5 +(acrothek)). Acrothek consisting of two seta fused to an aesthetasc.

Antenna ( Figure 16C View Figure 16 ). With basis about twice as long as broad, with inner longitudinal row of minute spinules. Exopod one-segmented, with three elements (apicalmost fused to exopod). First endopodal segment without armature; second endopodal segment with medial and apical outer hyaline frills; with two slender setae and two spines laterally, and with seven elements distally (one spiniform element, three geniculate single setae, one slender seta and two (outermost) elements fused).

Mandible ( Figure 16D View Figure 16 ). Gnathobase with multicuspidate teeth, three spines and two lateral pinnate seta. Coxa-basis with three setae. Exopod one-segmented, with two lateral and six setae distally. Endopod two-segmented; first segment with two lateral setae; second segment with one lateral and three distal setae.

Maxillule ( Figure 17A–D View Figure 17 ). Arthrite of praecoxa with two surface setae, two lateral elements and nine distal spines ( Figure 17B View Figure 17 ). Coxa with epipodal plumose small seta, with two strong and three slender apical elements ( Figure 17C View Figure 17 ). Basis with eight setae ( Figure 17D View Figure 17 ) and with some spinules distally. Exopod represented by single seta ( Figure 17D View Figure 17 ). Endopod one-segmented, elongate, with two apical setae.

Maxilla ( Figure 17E–I View Figure 17 ). Syncoxa with three endites, with three elements each ( Figure 17G–I View Figure 17 ). Basis with two strong claws and two slender setae ( Figure 17F View Figure 17 ). Endopod three-segmented; first segment with two, second segment with one, third segment with two setae.

Maxilliped ( Figure 17J View Figure 17 ). Syncoxa with spinules as figured and with three setae. Basis with longitudinal row of inner spinules and with two inner setae; endopodal segment elongate, with long claw and two setae.

P1 ( Figure 18A View Figure 18 ). Coxa large. Basis with outer slender seta and strong inner spine. Exopod three-segmented; elongate, reaching tip of ENP1; first and second segments with outer spine; third segment with four elements. Endopod two-segmented; first segment elongate, about five times as long as broad and about twice as long as second segment, with one inner element on distal third; second segment elongate, about four times as long as broad, with two apical elements.

P2 ( Figure 18B View Figure 18 ). Coxa large, with spinules as shown. Basis with outer spiniform element. Exopod three-segmented; first segment with, second segment without inner seta; third segment with two outer spines and two apical elements. Endopod twosegmented, reaching tip of EXP2; first segment with one inner seta; second segment with three elements.

P3 ( Figure 19A View Figure 19 ). Coxa large, with spinules as shown. Basis with outer long seta. Exopod three-segmented; first segment with, second segment without inner seta; third segment with two outer spines and two apical setae. Endopod two-segmented, barely

reaching tip of EXP3; first segment with one inner element strongly serrate distally; second segment with three elements.

P4 ( Figure 19B View Figure 19 ). Coxa large, with spinules as shown. Basis with outer seta shorter than in P3. Exopod three-segmented; first segment with well developed inner seta; second segment with minute inner seta; third segment with two outer small spines, two apical and three inner elements as shown. Endopod two-segmented, reaching middle of EXP2; first segment with one inner element strongly serrate distally; second segment with three setae.

P5 ( Figure 20 View Figure 20 ). Large, not foliose. Exopod elongate, with four outer (proximalmost seta lost during dissection), one apical (lost during dissection), and one inner seta (lost during dissection). Baseoendopod with outer seta; endopodal lobe with three inner and two apical elements.

Male. Unknown.

Remarks

The Mexican genus presented herein could not be attributed to any of the known genera of Tetragonicipitidae given the following combination: (1) lack of any projection on either the first or the second antennular segment; (2) first antennular segment nearly as long as second to sixth segments combined; (3) antenna with basis, and without abexopodal seta; (4) female P5 not foliaceous, exopodite and endopodite separated; (5) P1ENP two-segmented, P1EXP three-segmented; (6) P2 – P4 EXP1 with inner seta; (7) P2 – P4 EXP2 without inner seta; (8) P2 – P4 EXP3 with four, four, seven setae/spines; (9) P2 – P4 ENP1 with inner seta; (10) P2 – P4 ENP2 with three setae/ spines each. Of particular interest is the lack of any projection on either the first or second antennular segment (which is shared with Pteropsyllus T. Scott, 1906 , Diagoniceps Willey, 1930 , Oniscopsis Chappuis, 1954 , Aigondiceps Fiers, 1995 , Nidiagoceps Fiers, 1995 , Odaginiceps Fiers, 1995 , Godianiceps Fiers, 1995 , Mwania Fiers and De Troch, 2000 , Neogoniceps Fiers and De Troch, 2000 and Tetragoniceps santacruzensis Mielke, 1997 ), the first elongate antennular segment (which is shared with Pteropsyllus T. Scott, 1906 , Phyllopodopsyllus T. Scott, 1906 , Laophontella Thompson and A. Scott, 1903 and Tetragoniceps Brady, 1880 ), and the not foliaceous female P5 (which is shared with Diagoniceps , Aigondiceps , Godianiceps , Laophontella , Mwania , Neogoniceps , Odaginiceps, Protogoniceps , Nidiagoceps and Tetragoniceps ). The above suggests a closer relationship with Tetragoniceps santacruzensis . The absence of any projection on either the first or second antennular segment and the elongate first antennular segment both in Tetragoniceps santacruzensis and Tarengoticeps yokotaanensis sp. nov. might indicate a close relationship between these two species. Also, these two species share the small rostrum and the lack of antennal abexopodal seta, and the shape and armature of P1EXP and ENP. However, these two species can be easily separated by the armature formula of P2– P3 (with inner seta on P2–P3EXP1 and EXP2, and with five setae on P2EXP3 and four setae on P3EXP 3 in Tetragoniceps santacruzensis , but with inner seta on P2– P3EXP1, without inner seta on P2–P3EXP2, and with four setae on P2 – P3EXP3). Unfortunately, the female of Tetragoniceps santacruzensis and the male of Tarengoticeps yokotaanensis sp. nov. remain unknown and nothing can be said about the sexual dimorphism of either species.

Mielke (1997) pointed out that the integration of Tetragoniceps santacruzensis into Tetragoniceps is questionable, particularly without knowledge of the female, and hypothesized a secondary loss of the distal outer projection on the first antennular segment, and agreed with Fiers’ (1995) view about the polyphyletic nature of Tetragoniceps based on the variability of the armature formula of the pereiopods, the shape of P5 and shape of the caudal rami. The Mexican material herein presented could not be attributed to any of the known genera given the combination of characters above and it is suggested to allocate the new species to the new genus Tarengoticeps gen. nov. Even though T. yokotaanensis sp. nov. and T. santacruzensis share some characters, it would be premature to unite them into the new genus Tarengoticeps gen. nov, without the knowledge of either the female of Tetragoniceps santacruzensis or the male of Tarengoticeps yokotaanensis sp. nov.